COLEOrXERA. 93 there appear to be many good characters which may be employed for purposes of classification, amongst others the enhirgement or not of the 10th joint of the antennae, the presence or not of spongy-pubescent foveae on the occiput, the terminal spur of tlie posterior tibiae — already used by Dr. LeConte — and the great variety in the modifications of the front in the males. In dcnticollis and virginicR the general forms of body and antennae are so similar that they could scarcely be separated, but the heads in the males are entirely different in the character of the frontal and clypeal modifications. EUPLECTINI.
The very minute insects included in this group form a very large and important section of the singular family Pselaphidae, and bear a very striking similitude to several genera of Staphylinidae, their general resemblance to the genus Edaphus being most remarkable and unaccountable ; the latter may, however, be distinguished by tiieir flexible and retractile abdominal segments, which are seven in number, while in the present group they are six in number and comparativelyrigid; the minute structural characters are, of course, of an entirely different nature.
They appear to be rather rare as a rule, and are only occasionally met with, which is due, probably, to their comparatively secluded and little known habits, and their very small size; many new species and genera are undoubtedly yet to be discovered within the territory of the United States. The sexual characters are well marked, and occasionally present very curious structures in the males ; these characters are not made use of to any great extent in the following scheme of classification, but are generally mentioned incidentally wlien sufficiently interesting.
The material employed is tiiat contained in the cabinet of Dr. LeConte, together with a still larger set kindly communicated by Messrs. E. A. Schwarz and H. G. Hubbard,- of Washington, and also a few specimens in my own collection. In the second mentioned was included one entirely new genus not contained in the collection of Dr. LeConte. The genera here considered are those having but a single tarsal claw, and may be distinguished by the following table, this being intended as a continuation of the one given in the Classification of the Coleoptera of North America, Sm. Misc. Coll. No. 507.
Cont. Part II. 3 December, 1884.
94 NORTH AMERICAN Tarsus iiuth a single claw; front of head not produced: antennae straight. First ventral segment much elongated ; prosternnm neither foveate nor carinate ; last joint of antennae abruptly very robust Trimium. First three segments of the abdomen sub-equal ; prosternum bifoveate ; last three joints of the antennae more or less gradually increasing in width. Eyespresent.
Prosternum not carinate Euplectus.
Prosternum and mesosternum having a distinct medial loii^'itiiiliiial carina ; tenth joint of antenna unusually long and conspiiuous. Thesium.
Prosternum carinate ; mesosternum not carinate.
Eyes well developed and large in both sexes ; antennae very slender, club very slender and elongate ; pronotum having two lateral canaliculations, but neither a transverse basal groove nor lateral loveae ; prosternum very short Faliscus.
Eyes small and very coarsely granulated in the male, rudimentary in the female ; pronotum wi)h lateial foveae and transverse basal groove, without lateral canaliculations ; club of antennae rnlmst ; prosternum very long Nicotheus.
Eyes wanting ; prosternum liaving a distinct medial carina. ..Eutyphlus. I liave, much to my regret, been unable to obtain Dr. LeConte's types of Trimium, and since Eutyphlus contains but a single wellknown species, it is proposed at the present time to treat of the four remaining genera alone. Reitter, in his recent tabular statement of the Pselaphidae, distinguishes bis genus Scotoplectus, into which he absorbs Eutyphlus Lee, by the abnormal shortness of the elytra ; as in Eutyphlus the elytra are normally much longer than the prothorax, I cannot witiiout further evidence make the change of name. EUPI.ECTUS Leach.
The species of this genus are more numerous and individually much more abundant than tliose of the others ; tliey are vei-y readily divided into two groups, depending upon the canaliculation or not of the pronotal disk. As a coincidence, and probably of no generic import, it is to be remarked tiuit the species witliout tlie pronotal canaliculation liavf the entire lower surface of the liead covered densely with long erect sensitive setae, wliile, with but one or two exceptions, these setae are entirely wanting in those with canaliculated pronotum. It is inferred tliat the setae are sensitive, since tlie tip of each is swollen into a bulbous knob, but why some of them should be provided with this additional sensory apparatus, while others, apparently similar in all other respects, should be entirely deprived of it, is one of the mysteries of nature which must probably forever remain unsolved.
COLEOPTERA. 95 The following table exhibits the arrangement adopted for the species under examination, but which before many years will represent, without doubt, scarcely more than two-thirds of the forms which will then be known, and it is even incomplete at the present day, as I have seen at least one undescribed species not here represented. In cavicollis there is a very feeble broadly impressed area in the middle of the pronotal disk, which appears to be a rudimentary canaliculation ; it is, however, so feeble that I have placed the species in the second group; its very distinct form of protliorax will distinguish it without trouble.
Pronotum having a distinct medial longitudinal canaliculation or elongated canaliculate puncture.
Under surface of head having a large pad of erect sensitive setae ; canaliculationofpronotumverynarrow,extendingwithequalwidthfromthe base to the apex 1. caiialicillatlis.
Under surface of the head without the large area of sensitive setae ; canaliculation short.
Form generally somewhat robust ; head strongly convex and deeply impressedhehindthefrontalridge;interocularsurfacenotdistinctly punctate.
Minute species, not exceeding 0.8 mm. in length. Forna robust ; color reddish-testaceous..... 2. piiniillis. Form moi-e slender; color dark blackish-castaneous ....3. debilis. Larger species, not less than 1.3 mm. in length. Prothorax longer than wide ; genae of head very long. 4. loiigicollis.
Prothorax about as long as wide.
Eyes small ; genae rather long ; form of body slender ; abdomen narrow, rather rapidly narrowed toward the base. 5. difiicilis.
Eyes larger ; genae much shorter ; form of body more robust ; abdomen broader, just visibly narrowed toward the base. 6. congener.
Prothorax distinctly wider than long.
Pubescence very coarse, erect, and conspicuous ; antennae long and very robust, strongly setose ; males having two elongate spines protruding from beneath the third ventral segment ; size large ..- 7. sexiialis.
Pubescence scarcely noticeable, very tine, short, and recumbent. Head wider than long.
Sides of prothorax broadly rounded throughout ; male having two spines protruding from beneath the third ventral segment 8. spinifer.
Sides of prothorax much more acutely rounded anteriorly, straight posteriorly 0. linearis.
Head as long as wide 10. interruptiis.
96 NORTH AMERICAN Form linear, depressed ; sides parallel ; head very large and flat ; eyes small ; genae long.
Head strongly punctate toward the eyes 11. COlllllieilS. Head not distinctly punctate; body extremely slender and linear; size very minute 12. pei'teiiuis.
Pronotnm not having a median canaliculation or punctiform impression upon the disk ; under surface of head having a dense pad of erect setae. Prothorax strongly transverse ; median impression near the base very large and almost circular, nearly one-half as long as the entire pronotum 13. cavicoUis.
Prothorax very moderately or feebly transverse ; posterior median impressionmoderate or small, strongly dilated laterally. Large species ; pubescence very short and dense, giving an opaque appearance to the integuments 14. crillitllS.
Integuments polished ; pubescence scarcely noticeable. Larger species, not less than 1.4 mm. in length.
Head very small 15. capitllllllll.
Head larger, as long and nearly as wide as the prothorax. 16. decoi'us.
Minute species, not exceeding 1.2 ram. in length.
Form very convex and rather robust ; prothorax rather strongly narrowed behind, sides very evenly arcuate anteriorly ; color pale reddish-testaceous 17. ai'CliatllS.
Form somewhat depressed ; color dark piceous-brown or piceousblack.
Prothorax distinctly wider than long ; sides feebly convergent posteriorly; color plceous-black throughout 18. leviccps. Prothorax nearly quadrate, sides jiarallel ; color of elytra blackishcastaneous, that of the remainder of the body piceous-brown. 19. ruficeps.
1. E. caiialicillatUS Lee. — Bost. Joum. VI. p. 107. — Form rather robust. Pubescence somewhat long, fine, and dense, pale fulvo-cinereous and rather conspicuous ; color of body pale ferruginous throughout, shining. Head rather small, slightly broader than long ; eyes moderate in size and prominence ; genae scarcely prominent, shorter than the eye, strongly convergentbehind;basebroaillysinuate;interocularsurfacepolished,somewhatasperate, extremely convex, having a conspicuous longitudinal medial canaliculation at the occipital declivity, and at more than one-third the length from the base, two very minute spongy-pubescent foveae, very close to the eyes, intermediate surface nearly three times as wide as the distance of either fovea from the eye, very strongly convex and prominent, abruptly, strongly, and conspicuously declivous at one-tliird the length from the frontal transverse ridge ; the latter strongly arcuate anteriorly, swollen longitudinally in the middle, where it bears a small acute dorsal tubercle ; innnediately behind this inter-antennal ridge and along the bottom of the declivity of the inter-foveal convexity there is short, transverse, posteriorly arcuate (•hannel dilated at the ends ; supra-antennal tuberculations moderate, angu-
COLKOPTERA. 97 late externally, each crossed by a minute chann(^l ; antennae robust, as long as the elytra, club relatively slender, second joint but sliglitly wider than the following, joints nine and ten sub-equal in length, distinctly longer than the eighth, the former three-fourths wider than long,, and two-thirds as wide as the latter, eleventh but slightly wider than the tenth, much elongated, acuminate ; under surface of the head with a dense pad of erect sensitive setae. Prothorax large and robust, widest just behind the middle, where it is as wide as long, and slightly wider than the head ; sides evenly and rather feebly arcuate anteriorly, nearly straight, minutely and irregularly denticulate posteriorly ; apex two-lilths as long as the pronotal width, and two-thirds as long as the base ; disk very convex, polished, finely, and sparsely asperate, having a narrow, strongly marked medial canaliculation, extending with equal width from very near the apex to the basal margin, and which is crossed at one-fourth the length from the base by a transverse straight channel of equal width and depth, which terminates laterally in rather small deeply impressed spongy-pubescent foveae. Elytra at base scarcely wider than the pronotum ; sides rather strongly divergent posteriorly and strongly arcuate ; disk very slightly shorter than wide, but slightly longer than the pronotum, very convex, shining, distantly and evenly asperate ; sutural striae strong, close> arcuate ; lateral striae nearly obsolete. Abdomen as wide as and shorter than the elytra; sides parallel and slightly arcuate ; margin narrow and flat ; surface very strongly convex, polished ; first dorsal with two rather long, fine, divergent carinae. Legs rather long and slender ; prosternum transverse, very flat ; anterior coxae conical and very long Length 1.1—1.2 mm.
Detroit, Michigan, 1; Odenton, Maryland, 1; Georgia, 2; CrescentCity,Florida,1.
This species, the description of which is taken from Dr. LeConte's type, a male, is so aberrant, especially in the structure of the head, anterior coxae, and in its short, broad, very convex abdomen, that it is questionable whether it is advisable to retain it in the present genus. The large lunate penultimate segment of the abdomen in the male is broadly depressed in the middle; the apical segment is partly enclosed by the preceding, as is usual, and is slightly wider than long. The species is widely diffused, but is apparently very rare. 2. E. pumilus Lee. — Bost. Journ. VI. p. 1 06. — Form moderately robust. Pubescence somewhat sparse, very short, recumbent, fine, and not conspicuous. Color of entire body ferruginous, legs and antennae paler. Head rather small; eyes rather large and prominent; genae not prominent, as long as the eye ; interocular surface confusedly and coarsely granulose, shining, raised abruptly far above the eyes, nearly flat above, narrowed anteriorly, strongly sinuate at the middle of the base ; having two very minute, round, spongy-pubescent fovene at two-fifths the length from the base, mutually much more distant than either from the eye, connected by an anteriorly arcuate parabolic channel of slight deptli, as long as wide ; inter-
98 NORTH AMERICAN me.liate surface moderately convex ; sai)ra-aiiteiiiial Inberculations small, somewhat prominent, connected by the moderately arcuate frontal ridge; antennae slender, but slightly longer than the head, club large, ninth and tenth joints equal in length, one-half wider than long, the latter one-third wider than the ninth, eleventh somewhat abruptly much wider, evenly conoidal, acuminate, elongated, as long as the four preceding joints together. Prothorax widest slightly in advance of the middle, very slightly wider than the head, and just visibly wider tlian long; sides arcuate anteriorly, nearly straight posteriorly ; apex about one-half as long as the pronotal width, and three-fourths as long as the base, both slightly arcuate; disk strongly convex, coarsely granuldse, shining ; having a large, deep, elongated, fusiform, medial canalioulation ; also having at one-third the length from the base a narrow, deep, posteriorly cusped, transverse groove, very slightly dilated at the middle into a fovea, and terminating at the sides in rather large, shallow, spongy-pubescent foveae. Elytra at base distinctly wider than the prothorax ; sides distinctly divergent posteriorly and rather strongly arcuate ; disk quadrate, rather convex, shorter than the head and prothorax together, smooth, almost impunctate, shining ; sutural striae strong, close, and arcuate, lateral short and feeble. Abdonien slightly narrower than the elytra ; sides nearly parallel and straight; border rather narrow and slightly inclined; surface rather convex, shining, impunctate; first three segments equal; first two dorsals witii two distant, excessively short, and feeble divergent carinae. Legs rather short and slender. Under surface of the iiead apparently with a few widely scattered sensitive setae anteriorly Length 0.7 mm. South Carolina, 1.
Described from Dr. LeConte's unique type.
This species greatly resembles dehilis Lee. in everything but color, and differs from it in its smaller size, more robust form, less smooth and polished integuments, and in the shape of the pronotum, which is slightly less narrowed anteriorly tlian in that S[)ecics. The carinae of the dorsal segments are so small and obscure that I am not absolutely sure of their existence, because of the somewhat imperfect condition of the type.
3. E. (lebilis Lee— Proc. Am. Phil. Soc. XVIL 1S7S, p. 386, No. '20.— Form slender. Pubescence sparse, short, cinereous, rather inconspicuous, with much longer, very widely scattered setae upon the abdomen. Color piceous-brown, antennae and legs distinctly paler, elytra slightly darker; integuments highly polished. Head small, slightly wider than long; eyes small, convex, and very prominent ; genae very small, rather acutely rounded, shorter than the eye ; base broadly and feebly sinuate throughout ; interocular surface abruptly and very strongly elevated, moderately convex above, not punctate ; having two small, deeply impress.ed foveae at one-half the length from the posterior angles, mutually slightly more distant than either from the eye, connected by an anteriorly arcuate, parabolic, feebly impressed, and narrow channel, which terminates completely in the foveae; supra-antennal tuberculations small, angulate, and not very prominent,
COLEOPTERA. 99 connected by a distinctly rounded, transverse, and somewhat feeble ridge ; antennae more than two-thirds longer than the head, slender, eighth, ninth, and tenth joints sub-equal in length, increasing uniformly and rapidly in width. Prothorax widest just visibly in advance of the middle, where it is as wide as long, and slightly wider than the head ; sides very feebly arcuate anteriorly and nearly straight posteriorly ; apex one-half as long as the pronotal width, and three-fourths as long as the base ; disk very strongly convex ; having a slender, medial, fusiform canaliculation attaining neither the apex nor the transverse channel ; the latter is at a little more than onefourth the length from the base, nearly straight, narrow but distinct, strongly and abruptly cusped posteriorly in the middle, and terminating at the sides in two rather large, rounded foveae. Elytra at base distinctly wider tlian the jjronotum ; sides almost parallel, rather distinctly arcuate : disk moderately convex, very coarsely and excessively faintly impressed, distinctly longer than wide, and nearly as long as the head ; sutural striae strong, arcuate, lateral extremely short, broadly impressed, and rudimentary. Abdomen distinctly narrower than the elytra ; sides parallel and straight ; surface impunctate, broadly convex ; first three dorsal segments equal, basal ones without any visible carinae. Legs rather short and slender. Length 0.7-0.8 mm.
Tampa, Florida, 3; Ciipron, Florida, 1.
The description is taken from Dr. LeConte's type, which is a female. I cannot distinguish Dr. LeConte's tenuis (1. c. No. 30) from this species by any characters which are worthy of mention. The lateral striae of the elytra appear to be much longer and stronger in some specimens than in others, and the pubescence is easily rubbed from the elytra. The head is noticeably broader in the males than in the females.
The identity of tenuis with the above-described form is rendered still more probable from the fact that two specimens before me, apparently not possessed by Dr. LeConte, and collected at Tampa on the same day, and therefore probably at the same spot as the specimen described by him as debih's, resemble much more closely, and in fact are almost exactly similar to his unique type of te7iuis from Capron. 4. E. loilgicollis n. sp.— Form slightly robust. Pubescence of head and prothorax very sparse, short, and inconspicuous, that of the elytra and abdomen rather long, fine, dense, and conspicuous, pale fulvo-cinereous. Color of head, pronotum, and antennae rufo-testaeeous, that of the elytra, legs, and abdomen paler, more flavate, rather ferruginous. Head lar^e, as long as wide ; eyes rather large, not very prominent ; genae slightly convergentand arcuate, much longer than the eye; base broadly and evenly sinuate ; interocular surface broadly, very strongly, evenly, and, in the posterior third, uninterruptedly convex, polished, coarsely, but rather feebly punctate at the sides, entirely impunctate along the middle ; having at twofifths the length from the base two very small and feebly impressed rounded
100 NORTH AMERICAN spongy-pubescent foveae, mutually one-third more distant than either from the eye, connected by an anteriorly arcuate convergent channel, which near the foveae is very feebly impressed, but which, behind the frontal ridge, is longitudinally widened, much more deeply impressed, and nearly transverse ; supra-antennal tuberculations large, callous, and prominent, angulate externally,each having behind the callosity a small, round puncture; connectedby the feebly arcuate, rounded, transverse, frontal ridge ; antennae one-third longer than the head, somewhat slender, club robust, ninth joint slightly longer than the eighth, twice as wide as long, three-fourths as long and wide as the tenth, eleventh as wide as long, slightly wider than the tenth, sides nearly parallel, abruptly and acutely produced in the middle at apex ; last joint of the maxillary palpi rather long, slender. Prothorax widest just before the middle, where the sides are just visibly convergent and feebly arcuate, then much more strongly convergent and feebly sinuate anteriorly, and moderately convergent and nearly straight posteriorly, feebly and minutely sinuate just behind the middle; apex fully one-half as long as the pronotal width, and three-fourths as long as the base; disk strongly convex, polished, impunctate, slightly narrower than the head, and distinctlylonger than wide; having just before the middle an elongated, oval, median puncture, and, at one-fifth the length from the base, a transverse, posteriorly cusped, very feeble groove, dilated at the point into a deep punctiform impression, and terminating at the sides in two small, very deeply impressed foveae. Elytra at base distinctly wider than the pronotum ; sides vfry feebly divergent posteriorly, and moderately arcuate ; disk slightly longer than wide, rather feebly convex, polished, impunctate; sutural striae deep, arcuate, lateral two -fifths as long as the elytra, distinct. Abdomen very slightly narrower than, and equal in length to the elytra; sides just visibly divergent posteriorly and straight ; border wide and very feebly inclined; surface rather convex, shining, very slightly and sparsely asperate; first three dorsal segments equal in length ; first two with two rather close divergent carinae, which are rather long and prominent. Legs rather long and slender. Length 1.3 mm.
Deer Park, Maryland, 1.
The description is taken from the uiii(|ue specimen which is a male ; the terminal ventral sejxinent is strongly convex, and the penultimate has a very deep transverse impressed channel; the posterior edges of the tiiird and toiirtli S('i;ments are sinuate and produced in tlie most complex and inde^crihuhle nuinner. The sjjccies is very distinct in appearance, because of the peculiar conformation of the head, with its very long genae, and also on account of the elongated prothorax.
5. E. diflicilis Lee. — Bost. Journ. VI. p. 100. — Form slender; sides parallel. Pubescence very fine, short, pale, moderately plentiful ; color of body rufo-testaceous ; legs and tips of antennae just visibly paler. Head rather large, as long as wide ; eyes rather small, but prominent ; genae large, convergent behind, much longer than the eye ; liase sinuate in the