AMERICAN COLEOPTERA. 217 



BLEDIVS Leach. 



The species of this genus may be naturally divided into several 

 groups, which have been already in part recognized by Schiodte,* and 

 described by him as distinct genera. The characters upon which these 

 groups are defined have been determined by the study of very limited 

 material, and will by no means serve for the natural arrangement of 

 our species. The first dichotomous character of Schiodte : 



I. — Terminal part of mandibles thick, with a strong sharp tooth 

 behind the apex, etc. 



II. — Terminal part of mandibles attenuated. 

 Would divide our large testaceous species which seem so closely allied 

 as to be distinguished only by mandibular and abdominal characters, 

 into two widely separated groups. The other characters used by that 

 excellent observer are also of difficult observation, or visible with cer- 

 tainty only on dissection. I have therefore rejected them in great 

 part and propose instead the following ; the groups are named after 

 the best known species pertaining to each. 



Prothorax with lateral edge well defined 2. 



Prothorax without lateral edge or prosternal sutures I. MANDIBULABIS. 



2.— Prosternal sutures obliterated ; fissures of front coxal cavities short, closed. .3. 



Prosternal sutures distinct 4. 



3. — Hind angles of prothorax wanting II. ARMATUS. 



Hind angles of prothorax obtuse V. CORDATUS. 



4.— Fissure of front coxal cavities short, closed III. SEMIFERRUGINEUS. 



Fissure of front coxal cavities long, open IV. ANNULARIS. 



Group. 1 . — mandibular is. 

 The species of this group are of large or moderate size, brownish- 

 testaceous, not shining, finely granulate, and not strongly punctured ; 

 the head is usually darker with a short impressed line at the vertex, 

 and an elevation at the base of the antennae ; epistome truncate at 

 tip, sometimes with a subapical tubercle, the mandibles are very 

 long, the apical part in some long and slender, in others compressed, 

 and rather suddenly narrowed near the tip; about the middle there 

 is a large ascending tooth; the labrum is broadly emargiuate. Pro- 

 thorax broader than long, truncate in front, sides parallel, suddenly 

 and strongly narrowed i'rom the middle to the base, which is narrow, 

 truncate and finely margined ; hind angles wanting; disc convex, with 

 a well-marked dorsal line; lateral edge indistinct; under surface convex, 

 prosternal sutures not visible, external fissure of front coxal cavities 



*Naturhi8t. Tidsskrift, 3d ser., iv, 171, (1866); Ann. Mag. Nat. Hist. 1867, 3d 

 ser., XX, 31. 



