MONOGRAPH OF WEST INDIAN STAPHYLINIDAE 169 



Eetnarks. — This species is not strongly differentiated from the 

 others but is perhaps a little more readily recognized because of its 

 dull surface. 



The Trinidad specimens were taken in a cave (principally near the 

 mouth) at an elevation of 2,600 feet. 



XXIII. Genus HOLOTROCHUS Erichson 



Holotrochus Erichson, 1840, p. 757. 



Olotrochus DupoNCHEL, 1841, p. 57 (misspelling). 



Genotype. — Holotrochus volvulus Erichson (designated by Dupon- 

 chel, 1841). 



Dmgtwsis. — Body elongate, subcylindrical, glabrous; head not 

 margined or impressed; distal antennal segments transverse; labrum 

 transverse, broadly rounded ; mandibles rather stout, armed with two 

 teeth inwardly; fourth segment of maxillary palpus conical, as long 

 as first three together ; mentum hexagonal ; gular sutures united ; pro- 

 sternum narrowly produced between anterior coxal cavities but the 

 process is abruptly raised from presternum or abruptly carinate; 

 anterior coxal cavities open behind; coxae rather prominent, with 

 transverse sulcus on anterior face ; middle coxal cavities separated by 

 union of mesosternal and metasternal processes ; mesosternum strongly 

 carinate; metasternum impunctate; abdomen not margined; first and 

 second sternites absent, third carinate at middle; apical abdominal 

 segments appearing little different in the two sexes; tarsi 5-seg- 

 mented ; tibiae at most moderately expanded and bearing only a few 

 small spinules. 



Remarks. — This genus has apparently been both composite and 

 insufficiently distinguished from Osorius since its erection by Erich- 

 son. It then included volvulus and cylindrus from Puerto Rico and 

 crassicollis from Madagascar, and it was distinguished from Osorius 

 by having the anterior tibiae unarmed and the body glabrous. I do 

 not know crassicollis, but I have before me specimens identified in 

 the British Museum as cylindrus (which I confirm) and examples 

 from Puerto Rico which I believe to be volvulus. On the basis of 

 these specimens I come to the following conclusions: cylindrus is 

 distinct (generically) from volvulus by the structure of the prester- 

 num, as well as by its more fusiform and depressed shape and its 

 impunctate metasternum; cylindrus does not differ markedly from 

 all species of Osorius in the character of the front tibia but is always 

 glabrous. It can therefore be separated from Osorius (in which the 

 species without the tibial development are pubescent) by a combi- 

 nation of these two characters; cylindrus seems to represent more 

 nearly the accepted conception of Holotrochus, but volvulus was des- 

 ignated as genotype by Duponchel. 



449008 — 42 12 



