240 BULLETIN 63, UNITED STATES NATIONAL MUSEUM. 



Salient type-characters. — Elongate. Thorax rotundato-quadrate, 

 moderately convex; disc fineh' and sparsely punctulate; sides 

 rounded, posteriorly subsinuate; joosterior angles obtuse, anterior 

 angles acute and more or less acuminate. Elytra with dorsum 

 slightly convex, more strongly so laterally, scarcely sulcate, punctato- 

 striate, intervals with very few punctures. (LeConte.) 



Diagnostic characters. — Known by its elongate form and smooth 

 surface. Elytra not at all muricate; pronotum subquadrate, with 

 sides not strongly rounded. The elytra are not at all caudate. 



The prothorax is much narrower than in clentipcs. It is with more 

 difficulty separated from sponsa, and especially forma convexa (see 

 p. 215). Here its general form, glabrous integuments, and finer punc- 

 tuation must be depended upon. The character of the sculpturing 

 is the most important. Occasionally rather strongly punctate ex- 

 amples are met with, but the sculpturing is simple ; if muricate it 

 is to be referred to sponsa. Sponsa forma convexa is smooth, and 

 here the interstitial punctures are usually large and somewhat in- 

 dented. 



Var. distans is usuall}^ more robust and has thicker integuments, 

 and is found in a different geographical region; the elytral inter- 

 vals are wider and the punctures are very distinctly defined. 



For other specific differentiations consult the diagnostic characters 

 of Group A of the present subgenus. 



I can not see that gracilis has any close affinity or resemblance to 

 lucce as suggested by Doctor Horn. 



The specimens collected in Lower California and referred to this 

 species by Dr. George Horn" and in the collection of the California 

 Academy of Sciences, do not belong to this species at all, but to a 

 distinct species described in this paper as tibialis. 



I doubt that true gracilis occurs in Lower California. All data 

 thus far collected are surely negative. It does occur in the State of 

 Sonora, Mexico, and might possibly extend westward upon the 

 peninsula. 



The mentum is moderate. The middle lobe is rather short and 

 somewhat equilaterally triangular, with apex rather narrowly 

 rounded; at times reflexed at tip so as to appear truncate; surface 

 coarsely punctate, rather broadly and feebly convex centrally and 

 more or less distinctly foveate laterally, not noticeably setose. 



The prosternum is variable; convex between and behind the coxir, 

 sometimes feebly mucronate. 



The mesosternum is more or less arcuately precipitous or oblique, 

 and more or less concave. 



"See Proc. Calif. Acaa. Sci., 2d ser., IV, p. 349, 



