246 GEO. H. HORN. 



the anterior cl%w being less distinctly toothed than the anterior claw 

 of the front foot, the posterior claw is also less angulate. The pos- 

 terior claws are more neai'ly alike, the apical ])orti()n being somewhat 

 irregular as in reflexlpennls, with a quadrangular tooth at base, which 

 is less developed on the posterior or inner claw. 



The claws are similar on all the feet in the female, being more 

 slender than in the male and merely a little broadened at base. 



The variation in color has already been alluded to as dependent 

 more on the mode of preparation than to any real difference in freshly 

 captured specimens. No specimen is ever truly piceous. 



The punctuation varies to a degree which has caused the separa- 

 tion of forms unnecessarily. In Northern specimens (Canada) the 

 punctuation is well marked, although no specimens have been seen 

 in which there is any sharpness of definition or closeness of punctua- 

 tion seen in nearly all the other species. The more we approach the 

 warmer regions of the South (Arizona and California) the smoother 

 the specimens become, and in some of them it is nearly impossible 

 to detect any punctuation at all. 



The rather small size of this species will enable it to be readily 

 known at a glance from the others, except the immature forms of 

 ochraceus, but the sternal structure will enable it to be separated. 



The preceding remarks will explain the reason of uniting cristatus 

 and pedoralis with the present species. In my former essay these 

 were separated on the sculpture and form of mesosternal lamina, 

 which are now seen to be variable either from locality in the case of 

 .sculpture, or sexually in the form of the mesosternal lamina. 



Several species described by Motschulsky are considered identical 

 latiusculus, obtimusculus and maciilifrons. 



Zinnnermann (Trans. Am. Ent. Soc. ii, p. 250) has placed nebu- 

 losus as a synonym of HijdropliUm pijgmceus Fab., described from 

 meridional America, without any good reason for so doing, although 

 the descrijjtion will not only fit this species, but quite a good number 

 of others within the limits of the Fabrician acceptation of Hydro- 

 philus. 



Occurs from Canada and the N. E. States to Texas, Arizona and 

 California. 



P. ocUraceus Mels. — Elliptical, less couvex, shiniug, pale piceous, or piceo- 

 testaceous, head always piceous with a paler space iu front of each eye, the cly- 

 peus of male paler. Thorax distinctly and moderately closely punctate, the 

 ai'cuate and transverse series of coarser punctures barely distinct, the basal mar-- 



