MORGAN HEBARD 209 



The males from Topock, Arizona, and Needles and San 

 Diego, California, are the smallest of any before us and, in 

 addition, differ from the usual type in having the pronotal mark- 

 ing dark and striking, solid caudad with dots and lines cephalad 

 much as in paler examples of genitahs. In these the interocular 

 space varies from one-half to four-fifths as wide as the inter- 

 ocellar space, excepting in the San Diegan individual, in which 

 the interocular space is slightly but distinctly wider than that 

 between the ocelli. It is, therefore, clear that, in the regions 

 where the distributions of crratica, apacha and genitalifi coincide, 

 determination of males can be made with safety by relying on 

 the character of the concealed genitalia alone. 



The extremes of size variation in males of this species is shown 

 by the following table, as well as an approximately average 

 series from Deming, New Mexico. The species ranges from 

 what we term medium, to very small for the genus. 



Measurements (in millimeters) 



cf 



San Diego, California . 

 Topock, Arizona (4).. . 

 Deming, New Mexico 



(11) • 



Roosevelt, Arizona. . . . 

 Sabino Basin, Santa 



Catalina Mountains, 



Arizona 18 5.3 8.6 21.1 8.9 



We find that erratica very seldom approaches the minimum or 

 maximum given. In the latter extreme the size approximates 

 that of individuals of the maximum size developed in tonkawa, 

 which in that species, however, are apparently of frequent occur- 

 rence, particularly in northern Texas. 



In males of erratica the interocular space is usually about 

 three-fifths as wide as that between the ocelli, but varies from 

 one-half as wide to distinctly wider than that dimension, the 

 latter condition being, however, very rare. In females the inter- 

 ocular space is very slightly greater than that between the ocelli, 



TRANS. AM. ENT. SOC, XLVL 



