March, i9i6.] Hebard : Genus Stenopelmatus. 75 



the species, others with genitalia in the unformed stages are some- 

 times quite large. At present the general heaviness and solidity of 

 the limbs appears the only means of separating adults from some of 

 the nearly adult examples. 



In the present species megacephalism is often found in adults, 

 particularly of the male sex. This is always accompanied by a pro- 

 portionate broadening of the pronotum, which occurs principally in 

 the cephalic portion. The unusually globose occiput, occasionally 

 protruding bead-like eyes (normally very little protruding) and more 

 than usually roughened exposed portion of the jaws, give individuals 

 in which this condition has reached its maximum, a very singular ap- 

 pearance. 



At high elevations in Texas, New Mexico, Arizona and appar- 

 ently generally in southern California, the limbs are found to average 

 somewhat stouter and shorter than in other portions of the insect's 

 distribution. This feature is, however, decidedly variable. The 

 limbs of fnscus average distinctly shorter and stouter than in .S. talpa 

 or longispina. 



The caudal tibiae have their dorsal surface very weakly convex to 

 weakly concave, the spines vary from minute and delicate to stout and 

 heavy, while the distal spurs also vary both in stoutness and in length. 

 Normally the spines increase slightly in length distad, the fifth disto- 

 internal spine being much smaller than the others only in the abnor- 

 mal condition discussed in the next paragraph. 



Some of the females before us from southern California show a 

 striking abnormality in the greatly enlarged third spine of the dorso- 

 internal margin of the caudal tibiae, in extreme cases this spine being 

 longer than any of the distal spurs. This feature is also shown by 

 the series before us to exhibit great variability and though possibly 

 indicating incipient racial development, has by no means reached a 

 condition of sufficient stability to warrant nominal designation. 



The spine count for the dorsal margins of the caudal tibiae in the 

 series before us is as follows \^ 



Number of spines, internal 2-5 3-5 4-4 4-5 5-5 5-6 



Number of specimens i 2 8 19 89 5 



Number of spines, external 2-3 2-5 3-3 3-4 4-4 4-5 5-5 



Number of specimens 5 i 74 28 14 i i 



1 One specimen with a malformed limb has two instead of the normal 

 three pair of distal spurs, the pair of much smaller disto-ventral spurs are rep- 

 resented by three minute spurs. 



