1914.] NATURAL SCIENCES OF PHILADELPHIA. 69 



development, which in its details are not always correlative with 

 apparent affinities. These diversities can be placed in two categories, 

 one {mexicana, falcata, durangensis, castanea, and brevihastata) with 

 the plate entire, the other (comprising the remaining species) with it 

 divided completely in two, at least as far as the chitinous portion is 

 concerned. In the first section we have from an extreme which is 

 very broad and short, with the distal margin emarginato-truncate, 

 to one of a similar general form with the margin bisinuate to arcuato- 

 emarginate. In the second section we have even greater diversity, 

 the paired lobes varying from broad to very narrow, blunted to 

 aciculate, the general form of the margins differing to a lesser degree. 

 In the forms with an entire subgenital plate, the distal margin has a 

 different appearance when the plate is flat or when it is compressed, 

 which factor should always be considered in determining the character 

 of this margin. For the sake of uniformity, we have endeavored to 

 give the character of this margin from the plate were it flattened out. 



Notes on Tegminal Structure. — In the male the tegmina are more 

 ample in oreoeca and more reduced in size in tridactyla than in the 

 other species. The angle of the sutural margin is very greatly pro- 

 duced in tridactyla and on the other hand almost imperceptible 

 in catinata. The stridulating vein is apparent in all the forms 

 of the genus, but variable in strength and curvature, while the 

 tympanum is also of variable form and definition. In the female 

 the considerable variation in form and position indicated in the 

 generic description is not correlated mth the general relationship 

 of the forms, as certain species with overlapping quadrate tegmina 

 and others with nearly contiguous similarly shaped tegmina occur 

 in sections of the genus which on «um total of characters are well 

 removed from one another. The reduction of the female tegmina 

 has proceeded further in emarginata than in any other form of the 

 genus, as there they are decidedly lateral and very small, while the 

 development of the tegmina in the same sex is most marked in falcata, 

 where they are overlapping, covering all of the metanotum and the 

 greater portion of the proximal dorsal abdominal segment. The 

 venation in the female tegmina is always generalized, being more 

 complex in falcata than in any of the other forms. 



Color Pattern. — The color pattern of all of the forms of this genus 

 is similar in several respects; first, in the possession of pale paired 

 lines extending from the eye caudad to the apex of the abdomen and, 

 second, in the general uniformity of the lateral and ventral color. 

 In the majority of the forms the color of the dorsum between the pale 



