MORGAN HEBARD 53 



plate under the supra-anal plate, a single small chitinous thorn is 

 found. 



NEOBLATTELLA Shelford 



The present is one of the largest American genera of the Blattidae. 

 The great variety of species form groups which are distinctive in 

 various ways, a number (jf these possessing features which, in differ- 

 ent groups, show di\ergence toward different allied genera. Due 

 to the fact that none of the species are strikingly colored, while in 

 tropical Arherica a number of species belonging to the same group 

 may occur at the same locality, it is often difficult to associate the 

 sexes. The males show a most astonishing diversity of genitalic 

 development. In the groups studied, however, the Nahua (jroup 

 alone shows the dorsal surface of the male abdomen in any way 

 specialized, while in all the species of the genus, the paired plate 

 beneath the male supra-anal plate is unspecialized. Ignorance of 

 the value of genitalic characters alone has made the descriptions 

 of males by past students difficult to work with. 



The females, however, show little or no response to such special- 

 ization in the opposite sex, and accurate specific determinations 

 can be made only by the most careful study of other, and usually 

 much less distinctive, features of difference, combined with a 

 knowledge of the usual differentiation between the sexes, large 

 series for comparison, and, if possible, field knowledge of at least 

 some of the species. 



In the material here under consideration two groups are repre- 

 sented. A third, the Carrikeri Oroup,"" undoubtedly occurs in 

 Panama, material of this group from Costa Rica as well as from 

 Colombia being at hand. 



Neoblattella fratercula Hebard 



1916. Neoblattella fratercula Hebard, Ent. News, xxvii, p. 159, figs. I and 2- 



IcT, 9 ; Isla de Cocos, Costa Rica.] 



The present species is an aberrant member of the Impar Group 

 of the present genus, which group includes a great number of spe- 

 cies of medium small size, in which the sexes are but little dissimilar 

 and the tegmina show distinct cross-veinlets, particularly distad. 



^oSee Hebard, Trans. Am. Ent. Soc, .\lv, p. 100, (1919). 

 MEM. AM. ENT. SOC, 4. 



