MORGAN HEBARD 5 



species, and additional males of Eremoblatta hirsuta, the unique 

 specimen of that sex having suffered from immersion in alcohol. 



Diagnostic Values 



In considering the various diagnostic features, the most impor- 

 tant discovery has been that of the superlative value in many genera 

 of the Pseudomopinae of the form and specialization of the median 

 and dorsal abdominal segments in the male sex. In a number of 

 the species of the genus Parcoblatta the specialization there found 

 proves, by far, the most valuable character for separating males. 



The characters generally considered in the present paper and 

 their general values are as follows : 



Size individually often variable; showing occasionally some 

 slight geographic significance. 



Form moderately constant; in many species very different in 

 the two sexes. 



Head with shape often of some generic importance, usually 

 difficult to describe. Slight differences are usual between the 

 sexes; very decided differences are found when, in the same species, 

 the males have the tegmina and wings fully developed and the 

 females have these organs decidedly reduced or entirely absent. 

 In such cases the females have the head much simpler than the 

 males. 



Interocular space occasionally decidedly variable, but some- 

 times of diagnostic value; width best compared with width be- 

 tween antennal sockets, or with that between ocelli, when these 

 arc present. 



Ocelli showing few specific diagnostic features, but differing 

 decidedly in many genera and groups. Usually fully developed 

 in individuals having fully developed tegmina and wings; when 

 reduction in the organs of flight occurs, the ocelli are found to 

 exhibit a similar degree of reduction, and in species or sex showing 

 decidedly reduced or atrophied tegmina and wings, they are usu- 

 ally represented by mere pale spots. When the organs of flight 

 are absent, either in Iwth sexes or only the females of a species, 

 the ocelli are absent in the majority of forms, present, though greatly 

 reduced, in few. 



MEM. AM. ENT. SOC, 2. 



