114 Mr. D. Sharp's revision of the species 



nate, sternal spine, and by the denser and more even 

 punctuation of the upper surface, there being in T. 

 fuscitarsis but little difference between the punctuation 

 of the thorax and the wing-cases, this being very close 

 and fine on both these parts, and even denser on the 

 thorax than on the elytra. The systematic punctures on 

 the side of the prothorax seem to be in this species 

 more variable than usual ; sometimes there are three or 

 four of them forming a short irregular line, while more 

 usually they are concentrated into a small fossa. 



Group 10. Epipleural margin quite destitute of sculpture 

 or spines. 



The interesting species isolated to form this group 

 makes a slight approximation to the genus Pleurhomus 

 by the quite smooth epipleural margin. 



33. Tropisternus tinctus, Sharp. 



Sharp, Biol. Cent. Am., i., pt. 2, p. 59. 



Mexico. 



This species is readily identified by the complete 

 absence of sculpture on the epipleural margin, and by 

 the fact that the edge of the epipleura on the basal por- 

 tion of the wing-case, when seen beneath, forms a less 

 sharp edge than usual. There is an extreme sexual 

 difference in the sculpture of the mentum, this part in 

 the male being densely and finely rugulose-punctate and 

 opaque. 



Pleukhomus, n. g. 



Structura fere generis Tropisterni sed elytrorum epi- 

 pleuris pone coxas posteriores omnino angustis, hand ad 

 faciem elytri interior em applicatis ; margine epiplenrali 

 omnino laBvigato. 



I have separated two species from the other Tropisterni 

 on account of a peculiar structure of the margin of the 

 wing-case. In the species of Tropisternus the epipleura 

 behind the posterior coxae is folded in, so that a line 

 (which is the inner or lower margin of the epipleura) is 

 seen running along the inner face of the wing-case at a 

 little distance from its outer edge. In the two species of 

 Pleurhomus this is not the case ; the epipleura behind the 



