Horn] 382 [!„.,._ „,_ 



A Monographic Revision of the Species of Cuemastochilus of the 



United States. 



By George H. Hokn, M.D. 



(Read before the American Philosophical Society, Dec. 19, 1879.) 



In the Trans. Amer. Ent. Soc. 1871, p. 339, et. seq., will be found a table 

 prepared by me of the species then known, after a short study, the object 

 of which was to present some means for their identification in a ready 

 manner, the descriptions being scattered in books, inaccessible to many, 

 and sometimes unintelligible, either from their brevity or want of apprecia- 

 tion of characters which have since come to be of greater value. The 

 above mentioned table was made use of by Prof. West wood (in his "The- 

 saurus Oxoniensis, " p. 58), who at the same time described a certain num- 

 ber of supposed new species, since which others have been described by 

 Dr. LeConte, so that the aggregate assumed quite formidable dimensions 

 for a genus so peculiar. 



The types from which Prof. Westwood's descriptions were made are for 

 the most part in the Royal Museum of Berlin, where I had the opportunity 

 of examining them, through the kindness of the curator in charge. The 

 descriptions appeared soon after my examination had been made, and left 

 nothing to be desired for their identification. 



Having had occasion to study the species more closely, I have seen no 

 reason for any great alteration of the table already given, further than to 

 add the new species and transpose one which seemed rather out of place. 

 The accompanying table is, however, made so full as to contain nearly all 

 the important characters of each species, so that the chances of a mistake 

 in identification are reduced as near as possible to the minimum. 



Before proceeding to the table it seems proper that the characters should 

 receive more extended notice and comparison, which can be accomplished 

 by considering the different members in order. 



The head is short, oval, rather deeply inserted in the thorax, the vertex 

 usually convex, the elypeus more suddenly deflexed, forming an angle with 

 the front. In planatus and saucius the bead is more exsert and presents 

 in each characters worthy of special observation, these are — the carina on 

 the middle of the elypeus common to both species, the supraorbital carina? 

 of the first and the sudden narrowing of the head behind the eyes in the 

 second. In neither species is there an obtuse ridge indicating the limits 

 of the elypeus and front, but the upper surface of the head is gradually 

 declivous in planatus and very convex in saucius. In pilosicollis, erinitus 

 and Knochii the front is rather flat and the limit between it and the elypeus 

 is indicated by an obtuse arcuate ridge, so that the elypeus seems suddenly 

 deflexed from the front. In leucostictus the front and elypeus are on the 

 same plane, nearly flat, while all the other species not already mentioned 

 have the front convex but to a variable degree. 



