258 BULLETIN 63^ UNITED STATES NATIONAL MUSEUM. 



laticollis, from which it is at times difficult to separate, but here the 

 form of the pronotum must be relied upon. 



Armata and m'dttarls have all of the femora armed, while in the 

 present species only the anterior bear a tooth. 



Dentines is undoubtedly genetically related to armata (see p. 262). 



The chief incipient races have already been sufficiently indicated 

 and must only serve as centers for cabinet arrangement, for the meso- 

 types are multitudinous and defy limitations. 



The middle lobe of the mentum is moderate and subtriangular, at 

 times sub-traj^ezoidal or more or le-^s parabolic, and varies independ- 

 ent of race or form; the apex is usually more or less distinctly arcu- 

 ate; surface coarsely punctate and very faintly convex and quite 

 narrow!}' but not strongly foveate laterally Avithin the margin. 



The prosternum variable; usually rounded between and behind the 

 coxse; frequently with a small, and less frequently with a well- 

 developed mucro. In forma confnis some specimens have it sub- 

 truncate and feebly compressed behind, with the angle mucroid. 



Mesosternmn quite obliquely precipitous and more or less concave. 



The abdominal process is subquadrate, slightly transverse and in 

 width about equal to the length of the third abdominal segment ; the 

 post-coxal part of the first is about equal to the second, and the latter 

 is about twice as long as the fourth. 



The abdominal salient is about a fourth of its width Avider than the 

 metasternal process. 



The metasternum Literally between the coxa? is about as long as the 

 width of a mesotibia at apex. 



The tibial grooves of the femora are well developed, with edges 

 more or less cariniform, and their floors vary in the degree of con- 

 cavity. Those of the profemora do not quite attain the femoral base ; 

 on the mesofemora the grooA'es extend inwards to about the basal 

 fourth and there the margins become evanescent before becoming con- 

 tiguous; on the metafemora they only attain the internal third and 

 there become evanescent before uniting. 



The tibia> vary greatly in sculpturing, at times very denselj^ and 

 coarsely muricate and at others rather feebW so. The articular cavi- 

 ties are nearly alwavs closed and the grooves are ahvays more or less 

 roughly sculptured with their floors more or less shining, and 

 variable in degi-ee of develo])ment. The external borders of the pro- 

 tibiae are more or less distinctly carinate, the mesotibia? scarcely at 

 all so. 



The tarsi are very Ajuiable in length and stoutness, even in the 

 same race. 



In an average typical specimen the protarsi are about a sixth of 

 their length shorter than a mesotarsus. Joints two, three, and four 



