398 MEMOIRS ON THE COLEOPTERA 



indicate this in the description, from which it may be inferred that 

 the frontal sulci are normally long and deep in fufaus, which is 

 besides an evidently larger species 10 mm. in length. 



Platidius Chd. 



The uniting of this genus which seems to be wholly peculiar to 

 the western parts of North America with Patrobus, is inexplicable. 

 Typically it bears no close resemblance to Patrobus, differing in the 

 more parallel and subdepressed form of the body, thicker palpi and 

 more developed mandibles, absence of deep pronotal foveae and in 

 the acutely pointed hind trochanters, which sometimes attain al- 

 most the length of the femora in the males; it differs also in the im- 

 punctate sterna. As a remarkable peculiarity, it should be stated 

 that a minute nick in the sides of the prothorax just before the basal 

 angles is usually evident and, in incisus, this becomes a rather con- 

 spicuous character; it seems to be wholly wanting in Patrobus, where 

 the hind trochanters are short and obtuse in both sexes. In Pla- 

 tidius the eyes are relatively smaller and much less prominent than 

 in Patrobus, and the feebly impressed latero-basal part of the pro- 

 notum is very finely punctulate or rugulose, contrasting greatly 

 with the coarse punctures of Patrobus. Our species are moderately 

 numerous and, so far as known to me, may be described as follows: 



Prothorax nearly as long as wide, subquadrate; size larger as a rule; hind 

 wings well developed 2 



Prothorax shorter, transverse and subcordiform; pronotum more sharply 

 punctulate and with the punctures extending from side to side bas- 

 ally ; hind trochanters shorter though acutely pointed 7 



2 Latero-basal part of the pronotum broadly, very feebly and subevenly 

 impressed and punctulato-rugulose 3 



Latero-basal part similarly sculptured, but with a more definite shallow 

 foveiform impression remote from the side margin, the carina less 

 obsolete than in the preceding section 5 



3 Mandibles smaller, less prominent. Body relatively broader than in 

 the two following, rather dullish, deep black, the legs black; head 

 large, elongate, nearly four-fifths as wide as the prothorax, the sulci 

 long, deep, extending to the middle of the epistoma; eyes moderate, 

 not very prominent; antennae black, extending well behind the tho- 

 racic base and rather thick; prothorax just visibly wider than long, 

 widest just before the middle, where the sides are rounded, thence 

 feebly converging anteriad and arcuately feebly converging poster- 

 iad, becoming very feebly sinuate, the edge sometimes feebly crenu- 

 late, feebly and narrowly reflexed, rapidly more broadly so near the 

 rounded apical angles; base as wide as the sinuato-truncate apex, 



