376 



It is, perhaps, well to specify that the ventral segment, 

 which in this memoir I call the ''first" or "basal/' is that 

 which is (except in a very few species) partially overlapped 

 by the hind coxae, and that consequently the "second" ven- 

 tral segment is the first which is entirely free of the hind 

 coxae. These are the first and second that are visible on the 

 middle line. 



I now pass to the discussion of the species of Ueteronyx, 

 which I divide into 8 groups, as follow : — 

 A. Front outline of head (viewed ob- 

 liquely from behind) not presenting a 



threefold convexity. 

 B. Antennpe consisting of only 8 joints. 



C. Claws bifid Group I. 



CC. Claws appendiculate Group II. 



BB. Antenn£e consisting of 9 joints. '■ 



C. Claws bifid Group III. 



CC. Claws appendiculate Group IV. 



A A. Front outline of head (viewed ob- 

 liquely from behind) presenting a 



threefold convexity. 

 B. Antennae consisting of only 8 joints. 



C. Claws bifid Group V. 



CC. Claws appendiculate Group VI. 



BB. Antennae consisting of 9 joints. 



C. Claws bifid ... Group VII. 



CC. Claws appendiculate Group VIII. 



Some of the above groups lend themselves to further 

 division into subgroups, which will be found characterized 

 under the headings of the several groups. In the present 

 paper I am able to deal with only the species of the first two 

 groups, but I hope to offer a paper to the Society next year 

 completing this revision of the genus. 



It is well to add the note that I am unable to specify 

 any satisfactory character by which the sex of a Heteronyx 

 can be confidently determined. The ventral segments in the 

 male form a flat surface, so that their outline viewed from 

 the side appears as a straight line. That outline is convex, 

 I think, only in females. In some species the basal joint of 

 the hind tarsi shows slight sexual distinctions, but so slight 

 as to be valueless for description. 



Growp I. 

 The Heteronyces of this group are comparatively few in 

 number, and they are all rare in collections. I have before 

 me more than one specimen of only three species, and more 

 than two specimens of only one species. I cannot associate 

 with this group any of the names given by the earlier authors 

 except Blanchard's name ruhescens, and I should not have 

 ventured on that identification if I had not been assisted by 

 the possession of specimens from the original locality (Kan- 



