Introduction to the Sytiopsis of the Acrididoc.. 258 



we soon find tliat it can not be included with any of the known forms. 

 Its chief characteristic lies in the dispoifition of the radiating folds. 

 The increase of the latter occurs, indeed, as in other similar and 

 related species, principally by intercalation, but the new folds do not 

 occupy the middle of the intermediate space, but approach nearer one 

 fold than tlie other, which gives it the appearance of bifurcation. 

 The fact, too, is remarkable, that the new folds, which in other species 

 rapidly attain the distinctness of the older ones, here retain their in- 

 feriority in size to a notable distance from their beginning. It differs 

 from .Orthis Jissicosta, Hall, in its smaller size, finer plications, and 

 transverse markings, as well as the unequal convexity of the valves. 



From the Iidrodudion to the Synopsis of the AcrididcK of North America. 



By Cyrus Thomas, Ph. D.>:'- 



Acrididce is the name of a family of insects belonging to the order 

 Orthoptera. This order embraces a large number of species, which dif- 

 fer much in appearance and characters, and are known in this country 

 generally by the common names, earwigs, cockroaches, devil's-horses, 

 walking-sticks, grasshoppers, and crickets. Each of these names, ex- 

 cept the next to the last, repi-esents a distinct family of the order, 

 thus : 



Earwigs Forficulixtrp. 



Cockroaches ,.Blattic/a:. 



Devils-horses NayiUdm. 



"Walking-sticks Phasmidce. 



Grasshoppers. -[ ^<^ridida^. 



Crickets OryUidm. 



It will be seen that the common name, grasshoppers, embraces two 

 families, Acrididw and Locustidce, but these are quite ea.sily distin- 

 guished from each other. Locustidce includes those species usually 

 found on the grass and trees, which have very long, thread-like anten- 

 nffi — generally longer than tlie body of the insect ; the tarsi, or feet, 

 are four-jointed, and the fejnale has an exserted ovipositor, more or 

 less curved and sword-shaped. Most of the species have vrings, yet 

 there are a number entirely wingless, which reside on the ground. 



Acridida: includes those species which usually reside on the ground. 



'' These explanations are so clear and instructive as to make them well wortliy a reprint. 



