460 



PROCEEDINGS OF THE ACADEMY OF 



[Oct., 



The range of the species is now known to extend from Las Vegas, 

 Nevada, and Death Valley, California, to Indio and Yuma, and from 

 the western portion of the Mohave Desert to at least the vicinity of 

 Tucson. 



Heliastus californicus (Thomas). 



A single female of this species taken at Pasadena, May 23, 1898, 

 by Fordyce Grinnell, Jr., has been examined. It is inseparable in 

 structure from San Diego individuals, but is decidedly different in 

 coloration, being hoary whitish with a little buff washing and marked 

 with umber, instead of being wholly deep wine-red with faint macu- 

 lations as in four individuals from the latter locality. The color adap- 

 tation of this species appears to be as great as or even greater than 

 in H. aridas. 



Heliastus aridus (Bruner). 



This species seems to make its appearance as the true deserts, both 

 Upper and Lower Sonoran, are reached, encroaching perhaps in less 

 desert-like surroundings in the San Jacinto Mountains. 



After comparing the original measurements of H. californicus and 

 aridus and examining a large series of material, although unfortunately 

 containing few californicus, it appears that several of the best characters 

 for separating the two species have been overlooked. The pronotum 

 of H. californicus is considerably more expanded laterad, and the whole 

 width of the thorax at the insertion of the median limbs is consider- 

 ably greater in proportion to the length than in aridus, while the 

 caudal femora are much slenderer and more elongate in aridus. 



The length of the tegmina, a character previously used in a diagnostic 

 sense, appears to be quite reliable, but the other differences given 

 here are probably of greater importance. 



The following measurements of individuals of californicus and 

 aridus may prove of interest : 



Southern California, 



Type (from Thomas), 

 San Diego, Cal., 



H. californicus. 



Length of Length of 

 body. pronotum. 



mm. 



mm. 



9 



Length of 

 tegmen. 



mm. 



Length of 

 caudal femur. 



mm. 



20.3 12.7 



20.5 5.4 20.6 12.6 



San Diego, Cal., 



15 



3.2 14.5 



8.7 



