AMERICAN COMPONENTS OF THE TENTYRIIN^ 44I 



derivatives of a common stem form, though undoubtedly dis- 

 tinct ; IcBvis is defined above from the original diagnosis and is 

 a larger species, with larger head, than any of the allied Ari- 

 zonian forms ; it is confined to the Colorado Desert, from which 

 region I have no material at present. The locality given by 

 LeConte for 7'ugtceps is San Jose, which is certainly a mistake, 

 Tejon being probably intended ; it is a widely isolated species, 

 not at all closely allied to any other, if I have properly identified 

 it, constituting a type apart from the others in general form and 

 details of sculpture. I have been forced also to define stibpu- 

 bescens and punctattis from the original descriptions of LeConte 

 and Horn ; they seem to differ very much from the others in pro- 

 notal sculpture, and especially in the punctuation of the elytra, 

 and may have to be separated subgenerically ; at present they 

 are represented by uniques as far as known to me. 



Micromes n. gen. 



With this genus begins a series of very small forms, differing 

 radically from Triorop/ms in having the epistomal lobe short, 

 broadly angulate and less fully clasped by the mandibles, the 

 latter being nearly similar in structure but without the bulbose 

 swelling at base and less strongly, though somewhat similarly, 

 toothed above, the left very feebly as usual. They also differ 

 in having the side margins of the prothorax narrowly convex in 

 section but not accentuated by a bead, reflexed or otherwise, 

 being continuously punctured from the upper to the under sur- 

 face. In the present genus the eyes are variably prominent, 

 coarsely faceted but not anteriorly emarginate, and there is no 

 trace of a supra-orbital carina. The antennas are slender, mod- 

 erate in length and of the same general structure as in Trio- 

 rophusy but the met-episterna are wider and intrude somewhat 

 upon the narrow epipleuras, reducing the width of the latter 

 anteriorly still further. The male sexual characters are pre- 

 cisely as in Triorop/mSy the basal segment of the abdomen 

 having a large central, densely pubescent depression or fovea. 

 The type of Micromes was described by Dr. Horn as a Stibia^ 

 but it is evidently not very closely related to that genus, as shown 

 by general form of the body, type of elytral sculpture and form 



Proc. Wash. Acad. Sci., October, 1907. 



