JAMES A. G. REHN AND MORGAN HEBARD 259 



longer than deep, humeral sinus suboljsolete, convex callosities 

 obsolete. Tegmina reduced, the innnediate base alone concealed 

 by the pronotuni in both sexes; in the male with entire stridu- 

 lating field exposed. Dorsal surface of abdomen with a strong 

 medio-longitudinal carina, this broken on the distal tergites. 

 Male penultimate tergite specialized. Male cerci large and heavy 

 with an internal tooth. Female with ovipositor elongate, almost 

 straight, showing a very weak upward trend, smooth and pol- 

 ishetl except dorsal margin distad, which is very feebly furrowed 

 with irregular oblique ridges; apex acute, median. Female sub- 

 genital plate simple. Prosternum unarmed. Limbs short and 

 heavy. Cephalic coxae armed with a heavy spine. Femora with 

 ventral margins armed with minute but stout spines. Cephalic 

 tibiae with dorsal surface armed along external margin with three, 

 sometimes four, stout spines. Caudal tibiae armed distad with 

 three pairs of short heavy spurs, of which the dorsal pair are 

 approximately as long as the heavier median pair. Plantula 

 very small, scarcely longer than broad, about one-fourth the 

 length of the metatarsus. 



The character of the specialization of the male genitalia is dis- 

 tinctive among the Decticinae. 



Acrodectes philopagus^^ new species (PI. XI, figs. 1, 2, 3, 4, .5, 6 and 7.) 



In addition to the numerous structural features which separate 

 this remarkable insect from all other known forms of the Dec- 

 ticinae, the unusual black and tan type of coloration readily 

 serves to distinguish the species. 



Restricted in distribution to the bleak crags and rock piles, 

 above timber line in the High Sierras, this species is of unusual 

 interest to the student of biological development under as se- 

 vere conditions as can be found in the United States. 



Type — cf ; Mount Whitney, Sierra Nevada, Fresno County, 

 California. Elevation, 13,800 to 14,200 feet. September 7, 1919. 

 (M. Hebard.) [Hebard Collection, Type no. 551.] 



In addition to the features given in the generic description, we would 

 note the following: 



Size smaller than that of Idioslatm hcrmanii (Thomas). Head with ver- 

 tex slightly wider than proximal antennal joint. Pronotum with latero- 

 caudal shoulders of disk broadly rounded, the metazona moderately -inflated 

 caudad, so that the caudal margin is evenly convex in caudal asi)ect, caudal 



31 From ^Kkfj-rAfOC, = a lover of the icy crags. 



TR.\NS. AM. ENT. SOC, XLVI. 



