CATALOGUE 



DERMAPTERA 



PAKT IV. 



Fam. 6. ACRIDID^. (Continued). 



The continuation of the Catalogue of this family is preceded by a 

 few remarks on some of its characters and by a synopsis of the genera. 

 Most of the species may be arranged in three groups, which are repre- 

 sented by Acridium Tataricum, Heteracris plorans and Caloptenus Italicus. 

 Acridium and Heteracris are distinguished from Caloptenus by the longer 

 hind legs and narrower hind femora. The fastigium or tip of the 

 vertex is generally hexagonal in Acridium and in the neighbouring 

 genera, but this character appears also in some of the Caloptenus 

 group. The Acridium group, with some exceptions, is also dis- 

 tinguished by the greater distinctness of the dorsal keel and by the 

 slope of the prothorax on each side, and by the absence of lateral 

 keels. The prosternal spine has very generally greater length in the 

 Acridium group than in the Caloptenus type, where in a few species 

 it is reduced to a slight transverse ridge; in Cyrtacanthacris it attains 

 its full development and is curved and oblique, but this character 

 appears also in Heteracris. The Heteracris group (which in some of 

 its forms has an affinity to the Tryxalida)) and the Caloptenus group 

 differ generally from the Acridium group in the conical tip of the 

 vertex, in the flat disk of the prothorax, and in the shorter wings. 

 The migratory and especially destructive locusts belong to Acridium 



a 



