the Old World CyrtacantliacrinL 



135 



morp1iolog7, and even his detailed descriptions of the species 

 lie had l)efore hioi are remarkable for their vagueness and 

 superficiality, rendering them to a large extent useless 

 and even misleading, as I am able to state after a study of 

 the majority of his types. 



A superficial glance at a collection of ^^ Acridium "- 

 species is sufficient to show the impossibility of keeping them 

 all in one genus, or even in three or four genera, while a 

 careful study of all morphological characters reveals a num- 

 ber of very important differences between groups of species 

 which must be treated as genera. Of those characters, one 

 of quite special value is the structure of the head, particu- 

 larly of the frontal ridge (tig. 2), which enables us to make 



Fig. 2. 



Front view of head; a, Acridoderes 



Bol. ; 6, Anacridinm 



(sgi/ptimn (L.)? '^f Valanga nigrieonds (Bunn.) ; d^ Patauya 

 siJLccincta (L.). X 4. 



the primary division of the group. Further, the shape of the 

 elytra and their reticulation (but not the venation, i. e, tlie 

 position and form of the principal veins, which is fairly uni- 

 form throughout the group) supply some excellent characters 

 of doubtless generic value. The shape of the prosternal 

 spine (fig. 3) is also, as a rule, of generic value, although 

 the variations in its structure are limited, and accordingly 

 it is used for separating groups of genera. A very great 

 importance is attached by me to the shape of the external 

 genitalia, especially of the male sex, as this is a character, 

 or rather a complex of characters, not likely to be influenced 

 by the external conditions. In some particular cases, genera 

 are aberrant from their nearest allies in other respects, as, 

 for instance, Orthacanthacris, which has very peculiarly 

 shaped hind legs. As a rule, the type of coloration is also 



