ORTHOPTERA. IOI 



CC. Head rounded at the union of the vertex and front ; front perpendic- 

 ular, or nearly so. (Fig. 93.) 



D. The terminal spine of the outer row of the posterior tibiae wanting 



(Fig. 94,/-') ; second abdominal segment smooth. II. CEdipodin.e. 



DD. The terminal spine of the outer row of the posterior tibiae present 



(Fig. 94, a) ; second abdominal segment granulated on the sides. 



(Fig. 95.) III. Eremobix.e. 



BB. Presternum tuberculate, or mucronate, or produced into a cone. 



C. Head rounded at the union of the vertex and front; front slightly re- 

 ceding; antennae filiform. (Fig. 99.) IV. Acriiux.e. 

 CC. Vertex extending horizontally in front of the eyes ; front strongly re- 

 ceding ; antennae more or less flattened. (Fig. 102.) V. Opomaeix.e. 

 AA. No pulvilli between the claws of the tarsi ; pronotum extending over the 

 abdomen. (Fig. 103. ) VI. Tettigix.e. 



Sub-family I. — Tryxalinae* 



In the linear arrangement of the sub-families of the Acrididae 

 there are placed first, i.e., lowest, a series of sub-families in which the 

 prosternum is unarmed. The Tryxalinae differs from the other 

 members of this series in that the representatives of it have the ver- 

 tex, conical and elongated, the front strongly receding, and the an- 

 tennae flattened. The antennae are inserted between the middle of 

 the eyes or farther from the mouth than their middle ; the eyes arc 

 usually longer than that part of the genae below them ; the posterior 

 lobe of the pronotum is usually shorter than the anterior part ; the 

 median carina is not at all crested ; and the last spine of the outer 

 row of the posterior tibiae is wanting. 



The characteristic difference between this family and the next, 

 the CEdipodinae, is in the joining of the vertex and front, as indicat- 

 ed in the table of sub-families given above. The following species 

 will serve to illustrate the Tryxalinae : 



Ackurum brevipenne. — This is one of the most grotesque of all our 

 locusts. The body is excessively elongated, being almost linear. In 

 fully grown female specimens it measures more than 40 mm. (1.6 in.) 

 in length ; and about 3 mm. (0.12 in.) across in the widest part. The 

 males are somewhat smaller. The head is greatly elongated, and 

 ascending; the front is very strongly receding ; the antennae are a 

 little .shorter than the head and prothorax, broad near the base, 

 acuminate at the apex, and triquetrous. The wings are small', 

 when fully developed the tegmina extend a little beyond the third 



Tryxalinae, Tryxaiis: tryxallis (rpvcaXXii), Greek name of these insects. 



