1919.] NATURAL SCIENCES OF PHILADELPHIA, 57 



always longer than metazona. Tegmina and wings fully devel- 

 oped. Prosternum with low median protuberance or slight trans- 

 verse ridge: mesosternal lobes separated by a distinct interspace 

 or subattingent : metasternal lobes separated by a narrow interspace 

 to attingent. Subgenital plate of cf very bluntly, moderately 

 or strongly conoid produced, hardly compressed. Cephalic and 

 median limbs short, slender. Caudal femora moderately robust 

 to slender, genicular lobes and angles not produced; caudal tibiae 

 with spines of external margin more numerous than those of inter- 

 nal margin. - 



Classification. — ^The features of greatest value in differentiating 

 the species of the genus are almost entirely structural, although 

 several color features are of relative, or even, in one case in one 

 sex, of primary importance. The most important feature, and 

 one which shows no intra-specific variation in this genus, is the 

 presence or absence, and strength when present, of lateral pronotal 

 carinse. In all but intertexta there can be no question of the 

 presence or absence of these structures, while in intertexta they are 

 weakly indicated. In certain species there is found, bordering 

 ventrad the paired dark lateral bars on the postocular region of 

 the head and the lateral lobes of the pronotum, a strumose line 

 or carina. This is distinctly indicated in texana and alacris, and 

 incompletely and weakly so in neo-mexicana and intertexta. The 

 lateral foveolae of the vertex are of taxonomic importance in the 

 depth of their indication, but there is some variation in this feature. 

 The general form of the fastigium, of the fastigio-facial angle 

 and the angle of the facial line are of value, but there is much 

 variation in the exact degree of these features, particularly in 

 that of the form of the fastigium. The proportion of length to 

 depth of the lateral lobes of the pronotum is a feature which has 

 considerable importance. The very slender or the average form 

 of the caudal femora are also features of value, but there is much 

 individual variation in that considered average, although the very 

 slender type is more constant. The antennae show certain specific 

 types which, however, are very difficult to compare satisfactorily. 

 The general form, whether average or very slender, is also an 

 important feature in this genus. We find so little wing length 

 variation that the relative form remains approximately uniform 

 within each species. 



- These are so variable in number (at least 15 to 24 on external, and 14 to 20 

 on internal margin) that they cannot be used as diagnostic features for the 

 genus. 



