lO NORTH AMERICAN BLATTIDAE 



indeed made a valiant beginning in the general study of the Blat- 

 tidae, but it is evident that time and material were lacking for 

 definite conclusions in much of the work accomplished, while his 

 untimely end left many of the vital problems untouched. 



Conclusions 



In considering these facts, it is at once evident that the males 

 of the Blattidae show a much more intricate development than 

 the females, affording many striking features, which are not only 

 of specific, but also of generic diagnostic value. Indeed, it is clear 

 that, in many cases, the great majority of diagnostic features, of 

 specific or even higher importance, are not to be found in the sim- 

 plified female structure. 



The primary male sexual characters are, in great measure, only 

 of the highest specific importance; but in the general type of the 

 concealed genitalia and of the styles, a certain amount of generic 

 or higher significance is often found. 



The secondary male sexual features which frequently have full 

 generic values are: head development, pronotal specialization, 

 character of tegmina and wings and arrangement of certain veins, 

 specialization of median and dorsal abdominal segments and (when 

 much more rarely decided sexual difference occurs) type of limb 

 armament. 



The reduced, atrophied or absent tegmina and wings of the 

 females of many species apparently show a wider differentiation 

 from the primitive than do the generally more intricately devel- 

 oped structures of the males. Study of the fossil Blattidae shows 

 few examples among the known forms in which decided reduction, 

 accompanied by truncation, of the tegmina occurred in the female. 

 The males of those species, however, were generally of as intricate 

 structure as those of the present day. 



Distribution and Number 



The Blattidae are found in North America but little north of 



the Canadian boundary. In the United States the native species 



are in most portions few in number, and no forms of this category 



are known from north of the southern portions of the great central 



