NORTH AMERICAN COLEOPTERA. 241 



Mesosteruum with a feeble transverse carina, sometimes elevated at middle 

 forming a slight pyramidal protuberance ; maxillary palpi not longer than 

 uiPhilydrns; tarsal claws simple C'ymbiodyta 



Mesosternum with a compressed conical process; maxillary palpi long and 

 slender; claws broadly toothed at base in male, less in female. 



Helocottibiis. 

 PHILYDRUS Sol. 



The characters of this genus have been so often and so well given, 

 that It is not necessary to dwell further at this time on tho'^e by 

 means of which the genus may be known from others to which it is 

 most closely related. Some few points will be alluded to here in 

 order to avoid their frequent repetition in the specific descriptions. 



Each species seems to be invariable in color, excepting such ap- 

 parent variation as may be due either to evident immaturity or the 

 mode of preparation for the cabinet. The five following-mr/na^».9 

 cuspidatm, ductus, comors and perplexm are ti-uly piceous in color' 

 the others are various shades, usually called testaceous, with the 

 qualifying adjectives piceo, brunneo or pale, according to the species 

 or specimen. 



The sculpture consists of a punctuation, very regularly disposed 

 over the surface, which is never coarse, nor is it ever densely placed 

 the distance between the punctures being at least their own diameter 

 and sometimes more, but in cmctus it is rather closer than usual. 



On the head in front of and within each eye is an arcuate row of 

 coarser punctures. ^J^he thorax has two series on each side of coarse 

 punctures, one beginning near the front angle arching inward and 

 backward toward the middle, the other row transverse beginnino- at 

 the middle of the lateral margin. At the base of the thorax Is 'a 

 fine marginal line very well marked in all the species, except nebu- 

 losus, cmctus and ochmceus, where it is extremely faint or entirely 

 absent. 



The elytra have four rows of coarser punctures, that one nearest 

 the side margin is very irregular and contains the most punctures 

 the three rows between this and the suture are more regular and with 

 fewer and more distant punctures. In some species these series are 

 very indistinct. All the species have the sutural stria well impi-essed 

 from the apex three-fourths to base, where it is gradually evanescent. 

 PI. iii, fig. 2. 



Sexual sti-uctures have been observed in nearlv all oui- species of 

 such an obvious nature that it is remarkable that no mention has 

 been made of them. In nearly all of our species the males have at 



TRAN.S. AM. ENT. SOC. XVII. (31) j^LY, 1890. 



