266 BULLETIN 63, UNITED STATES NATIONAL MUSEUM. 



narrowly loimded. Dorsal plate Avith a slight antero-posterior con- 

 vexity. 



Habitat. — California (Livingston, Merced County, July, F. E. 

 Blaisdell, Charles Fuchs; Fresno, collection of the California Acad- 

 emy of Sciences, and the collection of E. A. Schwarz; San Joaquin 

 County, D. W. Coquillett). 



Xumber of specimens studied. 22. 



Type in my own collection, female. 



Type-locality. — Livingston, Merced County, California. 



Salient type-characters. — Pronotum moderately convex; disc 

 smooth, very finely .and sparsely punctate; apex truncate; apical 

 angles dentiform, small, acute, and stronglv divergent ; sides moder- 

 ately arcuate in the anterior two-thirds, thence feebly convergent to 

 base, scarcely sinuate; basal angles almost rectangular and not 

 prominent. Elytra with j^unctures moderately fine, arranged in 

 rather closel}^ placed, feebly impressed series, intervals with similar, 

 sparsely, and irregularly placed punctures. The anterior femora 

 with an acute tooth, the middle with an obtuse process, the posterior 

 \\\i\\ a very small and obtuse salient. 



Diagnostic characters. — Form variable. It differs in a general way 

 from aiwiata by being more slender and usually considerably smaller, 

 and especially in having the teeth of the hind femora rudimentary 

 or obsolete, wdiile those of the mesofemora are distinct or rudimen- 

 tary, and no doubt obsolete at times, and such individuals {forma 

 suheclentata) are scarcely separable from dentipes. The thorax may 

 be as in typical armata or more or less constricted at base as in 

 dentipes. Individuals of arniida wnth normal femoral teeth occasion- 

 ally have the protliorax constricted nearlj'^ as in dentipes and can be 

 spoken of as forma sinuafa. 



No doubt but that impotens is a transitional form between armata 

 and derdipes., as it occurs chiefly at the periphery of the area of 

 distribution of armata. Dentipes appears to be found mainly be- 

 yond the area inhabited by armata. Some examples of impotens 

 have the general form of gigantea. 



General observations. — The middle lobe oi the mentum is rather 

 large, trapezoidal and slightly broader than usual, apex more or less 

 arcuate, and the surface evenly and feebly convex. 



The sterna and abdomen as in armata. 



The articular cavities of the protibia^ are more or less open. The 

 other tibiic and femora are as in armata. 



The tarsi may be slender or stout and moderate in length. 



The protarsi are scarcely a fourth of their length shorter than a 

 mesotarsus. First four joints subequal, the first apparently as long 

 as wdde, the others a little wider than long, and together about equal 

 to the fifth. 



