TESTUDO ELEPHANTOPUS. 65 raised occipital crest; it is 43 inches long, measured from the front margin of the intermaxillary to the occipital condyle, and 4 inches broad in its widest part, between the zygomatic arches. 1. The frontal region is perfectly flat, broad, passing into the very short snout, its greatest width (in front of the postfrontals) being as much as one half of the distance between the tympanic condyles. 2. The occipital crest is enormously developed; it rises abruptly above the level of the skull, is strongly compressed and scarcely attenuated behind, its extremity being broad and rounded. 3. The tympanic case, with the mastoid, is produced backwards, the- hind margin of the paroccipital forming a rather strong curve (fig. A, a). 4. A deep hollow on the lower surface of the occipital in front of the condyle (Plate XLIV. fig. A, J). 5. On the front margin of the temporal fossa, corresponding to the suture between parietal and tympanic, and immediately in front of the foramen carotidis externa, there is a large, prominent, concave rough tuberosity for the insertion of a portion of the temporal muscle (Plate XLII. fig. A, ¢); a broad and deep groove (d) separates this tuberosity from the zygomatic arch. 6. Tympanic cavity large, but constricted by the groove just described; the outer tympanic rim is subcircular, with a broad and deep notch (e) in the posterior part of its circumference for the passage of the Eustachian tube. 7. The columella is attached to, and rests upon, a long, straight, sharp ridge, which runs from the notch mentioned to the stapedial foramen. 8. The front margin of the intermaxillary projects beyond that of the frontal, but much less than in 7. elephantina ; so that the nasal opening, although still obliquely sloping downwards, is as high as broad. 9. The position of the choane is advanced forwards; yet, on the palatal view of the skull, a portion of them may be seen uncovered by the alveolar lamellz of the maxillaries (Plate XXXIX. fig. A). 10. The intermaxillaries are short, one half of the length of the maxillaries; their foremost portion is deeply hollowed out below, and vertically bent downwards to form the truncated beak. ‘The suture between the intermaxillary and vomer is immediately behind the inner angle of the alveolar edges of the maxillaries. 11. The palatal region is much less concave than in the Aldabra Tortoise, and divided along its middle by a high longitudinal crest. The triangular space of which the foramina palatina and the anterior extremity of the vomer form the points is nearly isosceles in shape, in accordance with the generally short longitudinal axis of the skull, Outer pterygoid edge (/') rather elevated and sharp. 12. Anterior surface of the tympanic pedicle deeply excavated.
13. Lower jaw with a double alveolar ridge; its symphysial portion simply vertical, without a backward expansion of the lower margin of the bone. ‘The parts of the angular and coronoid which face each other are closely approximate, leaving only a narrow cleft between them. Upper margin of the angular deeply excised. The cervical portion of the vertebral column is characterized by its relatively great length. All observers were struck by the length of the neck, which the animal is in the habit of erecting so that the head is raised above the level of the shell. The living animal can turn its head in this position to the right or left, reminding one of a Cobra K
66 THE RACES OF THE GALAPAGOS.
rising in a posture of defence. This slenderness of the neck is not due to an increase in the number of vertebrae (which is constant in Tortoises as in Mammals, and limited to eight), but to their elongated shape. In 7. elephantopus they are not quite so slender as in 7. vosmeri, but much more so than in the species from Aldabra. Also the spinal canal is narrower than in this latter round-headed form. The crests of the dorsalaswellasthoseoftheheemalsurfacearewelldeveloped,andsometimesaccompanied by low additional crests. All the articular processes diverge comparatively but little ; and those which in the Aldabra species are nearly perpendicular to the longitudinal axis of the vertebra, are oblique and much depressed in 7. elephantopus. In the atlas (Plate XLVI. fig. A) the lateral portion of the neural arch (column) is very much constricted, not broader than the zygapophysis, which is elongate and considerably longer than that part of the bone which forms the roof of the arch. The centrum (odontoid process) (@) is a rhombohedral body.
In the second vertebra the neural arch is remarkably compressed and elevated, also provided with a high neural crest. The third has a condyle in front, and a glenoid cavity behind. The fourth is biconvex. The fifth (Plate XLVI. fig. C) has a glenoid cavity in front and a condyle behind ; its median neural crest is low, and accompanied on each side by two other crests, which diverge in the direction of the posterior zygapophyses. The sixth (Plate XLVI. fig. D) has a glenoid cavity in front and a condyle behind; its dorsal surface is flat, without crest, whilst on its visceral surface a low crest is evenly continued along nearly the whole length of the vertebra. The seventh (biconcave) vertebra (Plate XLVII. fig, B) is distinguished by the high crest on its dorsal and visceral surfaces; in the middle of the vertebra the neural crest is split into two branches, diverging in the direction of the zygapophyses and leaving a deep triangular recess between them. The point of divergence forms a kind of summit (a) to this vertebra. The neural arch is deeply hollowed out (6) inwards of and behind each anterior zygapophysis to receive the zygapophysis of the preceding vertebra; but no perforation of the bone takes place as in the extinct species of Rodriguez. The eighth vertebra, with its bipartite anterior and single posterior condyle, and with its expanded hamate posterior zygapophysis, does not differ from that of the Aldabra species. The measurements of the second to seventh cervical vertebree are as follows :— 2nd. 3rd. 4th. Sth. 6th. 7th.
millim.
millim.
millim.
millim.
millim.
millim.
Mength oficentrum) (45.19 ee oe eee 55 67 85 83 85 74:
Depth of centruman ithe middle... 501... ee 34 28 27 27 28 53 Horizontal width of middle of centrum .................. 15 17 18 20 29 27 Wadth, of anterior condyle ganj.c.c5.. eae 15 20 19 on ak aes Width: of anterior glenoid cavity .2.....2...0.0 eee oh Bee be 30 34 40 Width. of posterioricondyle |. cmcd..s ee eee a a 27 32 37 in Wadth of posterior clenoidicavitway a2 .eteee ee 9 20 oe sat a 43 Distance of outer margins of anterior zygapophyses... 23 34 35 38 40 38 Distance of outer margins of posterior zygapophyses... 25 26 28 30 29 46
TESTUDO ELEPHANTOPUS. 67 Of the dorsal vertebre scarcely more than the measurements need to be noticed ; these are of some importance in comparison with the corresponding vertebra in other species and also with the cervical vertebree. The two heads of the first rib are slender, much divergent, leaving a wide triangular space between them and the first dorsal vertebra, The iliac bones abut against the pleurapophyses of the 9th, 10th, 11th, and 12th vertebree, counting from the first dorsal vertebra. Their distal extremities unite to form the protuberance for the articulation of the ilium. Length of centrum of dorsal vertebra :— Ist. 2nd. 8rd. 4th. 5th. 6th. 7th. 8th. 9th. 10th. llth. 12th. mm. mm. mm. Inm. mm. mm. mm. mm. mm. mm. mm. mm. 65 80 80 80 78 55 48 48 16 14 16 22 The number of caudal vertebre is twenty-three in two, and twenty-five in a third ; but in the latter specimen they are irregular, and asymmetrically confluent towards the end of the tail. Limb-bones.—In the scapulary (Plate LIII. figs. C, C’) we notice the ad Bs very obtuse angle at which the scapula and acromium meet. The body of the scapula proper is rather slender, compressed, trihedral in form, / with its anterior side convex, as shown in the annexed figure, which represents a transverse section through its middle. The coracoid is not J ankylosed to the scapula. The measurements of this bone are the following:— millim. Lengthofscapula(measuredfromthesuturewiththecoracoid)............200 Cincmimierence tarais middle. | year. 254 ees ckese nc cst lees Caos o,¥he ov nqoudea ees oes - 75 Longitudinaldiameterofglenoidcavity............FeeRecetasONtientAEN50 Memerin@ le COLAC tatrevienminyer may ain distisees tonMhgntiaelicehuesuieastcleatecets 86 CTeALent WIG AsOle COLA CONG a.
ereecui nto ay is acsn cuigede does coe hadek bawkoadidescabieces 70 erie EO i ACTOMMUMNU NM hans artes ena hy ee nae heat amcpleg Aged ages ven dennin cae 84.
The shaft of the hwmerus (Plate LI. figs. A, A’) is moderately slender, subtrihedral, with the edges well rounded off. There exists a deep impression on the outer side of the bone, immediately below the head and ulnar tuberosity (a), and another transverse impression on the hinder side above the trochlea. The ulnar tuberosity projects high above the head, which is nearly entirely raised above the level of the summit of the radial tuberosity. The canal (4) for the blood-vessels on the radial edge of the bone, close to the elbow-joint, is perfectly closed, perforating the substance of the bone from the front to the hinder side. millim. Lengthofthehumerus,measuredinastraightlinefromthesummitof the head to the middle of the trochlea 0.0.0.0. cccccccecscececesenccscecsceeecoss 216 Circumferenceofthenarrowestpartoftheshaft........000.0.0...cccceecease89 Momgest diameter of the head. ..........4sccsgceycsesconecescseuscesersecnceuceevess 40 Bhortestdiameter of the head. ......c6s.cceigse.ceee acecsstscavcescsecacees seen: 37 Extreme breadth between the condyles 2.0.0.0... 00.
ccc ccc eco cecc ccc eeecevecses 82
68 THE RACES OF THE GALAPAGOS.
The bones of the forearm do not show any noteworthy peculiarity ; but, for the sake of comparison with the other species, I give the measurements:—The ulna has a length of 137 millims., and a width of 28 millims. in its narrowest part; the radius a length of 121 millims., and a circumference of 50 millims., also measured in its narrowest part.
As in Testudo generally, so here the carpal bones (Plate LIII. fig. D) are arranged in three series, of which the proximal consists of two bones, lunare and cuneiforme, both articulating with the end of the ulna (wu); the middle, of the transversely elongate scaphoid and “ intermedium;” and the distal, of five small rounded,bones corresponding to, and articulating with, the five metacarpals. The scaphoid articulates with the end of the radius (7), the ‘“‘intermedium” being intercalated between the lunare and third digit. However, in the old specimen of this species there exists the peculiarity that the scaphoid and intermedium are coalesced into a single very long bone (a), and that the two radial ossicles of the distal series are similarly united (6). Pelvis (Plate LU.).—In the first place must be noticed the considerable horizontal width of the symphysial bridge (a) between the obturator foramina, by which the flatheaded Tortoises are so signally distinguished from the round-headed ones. But quite peculiar to this species is, first, that also the vertical diameter of this bridge is considerable and scarcely less than the horizontal, and, secondly, that, although all other sutures in this aged specimen have disappeared, the transverse suture between the pubic and ischiadic halves of the bridge is still persistent. The iliac bones are comparatively slender, the longitudinal diameter of the pelvis much exceeding the horizontal one. The lower part (2) of the pubic bones is gently inclined downwards and slightly concave above; it emits laterally a very long, strong, nearly styliform process (¢), which is obliquely directed outwards. The posterior part (d) of the ossa ischii is of considerable width, very slightly concave above, and provided with a trenchant symphysial crest below, which, expanding hindward, forms a large triangular tuberosity. Lateral margin of the ossa ischii excised in the shape of aC. Obturator foramina of moderate width, considerably wider than the bridge between them, which is not provided above with a median longitudinal crest.
millim.
Longestinnerverticaldiameterofpelvis(fromsummitofiliumtosymphysis)170 Longestinnerhorizontaldiameterofpelvis...............c.ececseeeeeeesBradrouaes132 Shortestinnerhorizontaldiameterofpelvis(betweenilio-pubicprominences)112 Longest diameter of foramen obturatorium:.|./29-9 cette pee eee Width of symphysial tbridge: :, 2.55, See ee ee ee eee 26 Depth/of:symphysial bridge: «4. 55.) Sass coke ace eee eee 26 Leastbreadthofposteriorportionofossaischit.7.......1....-07-4----1224s)eee61 Length Of 08S i. 2 5 eicecaeia lates nls eee ee eee 140 Least. breadth of 08 ait, i320. fen ccna eh ee ee eee 30 The shaft of the femur (Plate LIII. figs. A, A’, A”) is rather stout, nearly straight,
TESTUDO NIGRITA. 69 irregularly subtetrahedral, narrower in front than behind. The head has an elliptical form, and does not rise above the level of the summit of the larger trochanter, from which it is separated by a deep and broad cavity. The larger (a) and lesser (bd) trochanters are confluent into one broad ridge, and not separated from each other by a smooth groove as we shall find to be the case in some of the following species. The length of the femur in this example is 169 millims., with a least circumference of 80 millims.; the width of the condyles is 66 millims.
Of the lower leg no part needs to be mentioned particularly. The tidia is 136 millims. long, and the fidula 123 millims.
Also the bones of the foot may be passed over, with the exception of one point, viz. that, like some bones of the carpus, the astragalus and calcaneum are entirely coalesced, so that no trace of their former separation remains.
2.
TESTUDO NIGRITA.
No doubt can possibly be entertained as regards the correct application of this name to the species which I am about to describe. It had been given by DuM&rin and Biron (‘ Erpétol. Génér.’ ii. p. 80) to two examples, of which the smaller, very young one, is in the Paris Museum, whilst the larger, but also of young age *, is the property of the Royal College of Surgeons. Brsron’s description is almost entirely drawn up from the latter specimen, which, therefore, must be regarded as the type. However, I suspect that the very young example which Dumirit and Brsron have associated with this specimen should not be referred to this species, but possibly belongs to one of the Mascarene Tortoises. BiBRoN, in his description of its legs, omits all mention of the large scute in front of the elbow—a character which, as far as we know at present, is common to all Galapagos Tortoises, but is absent in the Aldabra species. Further, I am almost certain that the large skull described by Dr. Gray (Shield Rept. p. 6, pl. 34) under the name of 7estudo planiceps belongs to the present species, for the following reasons:—l. There is the circumstantial evidence that we are acquainted with the adult skulls of 7. elephantopus, T. ephippium, T. abingdonii, and T. microphyes, but not with that of 7. nigrita. ‘The skulls of the four former species have been preserved, together with their carapaces; but the skull belonging to the shell of our single adult individual of 7. nigrita is lost. As the skull named 7. planiceps differs in a marked manner from all the others, we may reasonably suppose that it is that of the last-named species. 2. The British Museum possesses skeletons of young 7. nigrita; and although the skulls of these individuals have not the specific characters well developed on account of their young age, they show a greater resemblance, especially in its narrower snout, to the skull named 7’. planiceps than to any of the others. * Brpron considered it to bé an adult example; and its relation to the Galapagos Tortoises appears to have escaped his notice entirely.
70 THE RACES OF THE GALAPAGOS.
The materials available for the description of this species are the following :— 1. A carapace without sternum of a very large example, 41 inches in a straight line ; it was purchased by the Trustees of the British Museum from the Manager of the former Surrey Zoological Gardens, who could not give any information as regards its history (Plate XXX. fig. 3B).
2. A carapace 22 inches long*; type of Testudo nigrita (D. & B.); property of the Royal College of Surgeons; history and sex unknown. I am indebted to Prof. FLowsr, F.R.S., for the loan of this specimen (Plate XX XI. fig. C). 3. Two perfect skeletons, with epidermoid plates, of young examples, the carapaces being 153 and 16 inches long. History and sex unknown. 4. A very young example, stuffed; carapace 84 inches long. This specimen was purchased of a collector coming from Chile, and therefore without doubt came originally from the Galapagos Islands. <A figure of it, somewhat reduced in size, has been given by Dr. Gray, under the name of 7. elephantopus, in Proc. Zool. Soc. 1870, p (03. plaly, 5. A very young example, stuffed; carapace 10 inches long. History and sex unknown. Received from the Haslar Collection.
6. A skull of a very large example, described and figured by Dr. Gray as T. planiceps(1.¢.).
The carapace of this species is well characterized by its broad, circular shape, great depth, and more especially by the numerous, deeply cut concentric strie, by which the areole are much reduced in size in immature examples, and which are persistent in considerable nnmber even in specimens of the largest size. Our largest example (specimen No. 1, Plate XXX. fig. B) is a carapace 41 inches long, unfortunately without the sternum. Nevertheless we can safely affirm that this individual was a male, as the females never attain to so large a size. It is only 8 inches longer than broad; and when measured over the curvature its transverse circumference even exceeds the longitudinal. ‘The areolar portions of the dorsal and marginal plates are perfectly smooth and raised above the general outline of the shell, especially those of the former; but each plate has a broad margin deeply sculptured with concentric and parallel strie, the outer striated margin of the marginal plates being even broader than the smooth areolar portion. ‘The first dorsal scute and the anterior half of the second are declivous, the declivity of the former being still steeper than that of the latter. A deep notch, nearly as deep as that between the two foremost marginal plates, exists between the first and second marginals; also the posterior margin of the shell is scalloped. ‘The length of the caudal plate is to its width as 11:14 (53 inches long and 7 inches wide); its surface is plane; that is, its posterior margin is not bent either *Brrrongives365millims.asthelengthofthisexample,whichisevidentlyamisprintfor565. + An example of about the same age is rather indifferently figured in SowrrBy and Lrar’s ‘ Tortoises, Turtles, and Terrapins,’ where it is named Zestudo indica.
TESTUDO NIGRITA. qa inwards or outwards. The general colour is a deep black, with a brownish tinge about the margins of the majority of the plates.
As in the preceding species, the shell is thin and light; in this specimen it is only 4 millims. thick in the middle of a costal plate. Specimens of the common Testudo greca only about 8 inches long have a carapace almost as thick as these gigantic Tortoises.
The second specimen (Plate XX XI. fig. C), which is 22 inches long and the type of T. nigrita, is young, and probably a male, inasmuch as the sternum shows a slight concavity, and the passage between the hind margins of the caudal and sternal plates is of inconsiderable width. As in specimens No. 3 (153 inches long), the carapace is deeply sculptured all over, the smooth areolw being very small. Its transverse circumference equals the longitudinal. The front margin, as well as the hind margin, is deeply notched, each notch corresponding to the suture between two marginal plates. ‘The outer surface of the caudal plate is convex, the hind margin being curved inwards; its length is to its width as 3:4. The sternum terminates anteriorly in a thickened, rounded, double-headed transverse knob, with a slightly concave surface below; and posteriorly in a deep rectangular notch. The colour is the same as in the adult example.
Our very young emample, which is only 81 inches long, and figured in Proc. Zool. Soc. /. ¢., agrees in every respect with those of more advanced age, differing from young examples of the same size of 7’. ephippium by the greater relative width of the carapace. The principal measurements of the specimens described are as follows :— Length of carapace. Width of carapace. Sternum. Caudal plate.
In str. line. Over curve. Instr. line. Over curve. Length. Width. Length. Width. in. in, in. in. in. in. in. in.
Se hoo tepictd as 41 52 33 53 re ee 54 7 Paola ame rere 22 27 16 27 184 153 3 4.
Same eros cat 154 194 11 19 12 92 Pare 13 16 214 124 21 144 114 24 3 41 ina 8+ 104 6 104 63 6 ii L The skull (Plates XLII.—XLIV. fig. D) is distinguished by its comparatively longer facial portion, and by the much-produced mastoid processes; it is (see also Gray, Catal. Tort. 1855, 4to, tab. 34) 54 inches long, measured from the intermaxillary to the occipital condyle, and 43 inches broad at its widest part, viz. between the tympanic processes. 1. Its frontal region is flat, narrow, its greatest width being two sevenths of the distance of the tympanic condyles. 2. Only the foremost part of the parietals forms a flat surface, the remainder being compressed into an almost trenchant crest, passing into the long narrow occipital spine, which is scarcely raised above the level of the skull (Plate XLIII. fig. D). 3. The tympanic case with the mastoid is produced far backwards, so that the paroccipital margin appears as a deep semicircular excision
72 THE RACES OF THE GALAPAGOS.
(Plates XLIII. and XLIV. fig. D, a). 4. A very deep hollow on the lower surface of the occipital, in front of the condyle (6)*. 5. On the front margin of the temporal fossa, corresponding to the suture between parietal and tympanic, immediately in front of the foramen carotidis externe, there is a large, prominent, flat, rough tuberosity (c) for the insertion of a portion of the temporal muscle; a broad, not very deep groove (d) separates this tuberosity from the zygomatic arch. 6. Tympanic cavity exceedingly large, especially its posterior portion, the entrance being somewhat narrowed by the groove just mentioned; the outer tympanic rim is a regular circle, with a shallow notch in its hinder circumference for the passage of the Eustachian tube. 7. This notch is very remote from the columellar foramen ; and a sharp ridge runs the whole distance from the notch to the foramen, serving as a rest for the auditory ossicle. 8. The front margin of the intermaxillaries projects beyond that of the frontals, but much less so than in the Aldabra Tortoises ; so that the nasal opening, although still obliquely sloping downwards, is scarcely higher than broad. 9. The inner nostrils are advanced, not very distant from the end of the snout, and on the palatal view of the skull are nearly entirely hidden below the alveolar lamella of the maxillaries. 10. The intermaxillaries are short, not quite one half of the length of the maxillaries ; and their foremost portion is deeply hollowed out below, and vertically bent downwards to form the truncated beak. The suture between the intermaxillary and vomer is immediately behind the inner angle of the alveolar edges of the maxillaries. 11. Palatal region much less concave than in 7’. elephantina, and provided with a rather high median longitudinal crest; posteriorly it is bordered on each side by the raised pterygoid edge, which is obtuse in its anterior, and trenchant in its posterior half. The distance between the foramina palatina is much less than their distance from the anterior extremity of the vomer. 12. Anterior surface of the tympanic pedicle deeply excavated. 13. Lower jaw with a double alveolar ridge, the symphysial portion being simply vertical, without a backward dilatation of the lower margin of the bone. The opposite surfaces of the angular and coronoid are closely approximate, leaving only a narrow cleft between them. Upper margin of the angular moderately excised. i The skull of a young example, 23°; inches long, shows some of the characteristics described in the adult skull, viz. the greater depth and the less width of the palatal region, the deep hollow in front of the tympanic pedicle, and the conformation of the anterior half of the tympanic cavity. The grcove between the temporal tubercle and zygomatic arch, as well as the hollow in front of the occipital condyle, are clearly indicated. On the other hand, the tympanic pedicles are less distant from each other than in the adult, the mastoido-tympanic process is only slightly produced backwards, and the occipital crest is short and much less prominent—points of difference which can be accounted for by the young age of the individual.
*InthefiguregivenbyDr.Graytheartisthasentirelyomittedtoexpressthedepthofthishollow by shading.