34 



be smaller or absent in the female. The last sternite is variably impressed and 

 carinate behind. It is considered by some that the first two sternites are fused 

 and hidden in the metacoxal cavities; in this paper the five visible abdominal 

 sternites are numbered from one to five. 



FIG. 4. HYLURGOPS PINIFEX FITCH; VENTRAL VIEW. ORIGINAL. 



C.C., coxal cavity; Cl.,club; E, EL, elytron; F., femur; Fun.,funicle; Gen.,gena; g.s.,gular suture; 

 L., labium; Md., mandible; M. ex., mesocoxa; M. epist., mesepisternum; M. epim., mesepimeron; 

 Meta. st., metasternum; Metepist., metepisternum ; M. st., mesosternum.; mx., maxilla; Fed., 

 pedicel; Pst., prosternum; P.m. st., process of the mesosternum; Sc., scape; Tr., trochanter. 



INTERNAL CHARACTERS. 



Considerable attention has been devoted to the application of internal 

 characters to taxonomy. The characters of the male and female genitalia, and 

 the alimentary canal, particularly the proventriculus, have been discussed in 

 papers by Lindeman, Verhceff, Sedlaczek, Nusslin, Fuchs, Hopkins, and others; 

 and these characters have been employed in arranging keys for determination 

 of genera and even of species. I have found these characters, especially the 

 proventriculus, of the greatest interest and much practical value; but a wider 

 study is apparently necessary, employing many genera and species, and parti- 

 cularly many specimens in each species, before definite conclusions can be drawn. 



The chief drawback to the employment of these internal characters, and 

 likewise of the mouth parts and hind wings, lies in the difficulty of their examin- 

 ation. While it is easy enough to make excellent mounts of the mouth parts, 

 proventriculus and genitalia of Crypturgus atomus, if one has the proper equip- 

 ment, it is quite impossible for the average student or forester, and a detailed 

 discussion of these characters is therefore omitted from this paper. 



