REVISION OF ELEODTINI BLAISDELL. 75 



Ventrolateral surface (Plate 2, fig. 4) moderately convex, slightly 

 concave laterally before the apex; surface sparsely punctate and finely 

 setose; siibmargmal groove well developed beneath the explanate ex- 

 ternal border of the dorsal plate, passing obliquely inward beneath 

 apex to the inner angle of the fossa, ending at the internal apical 

 lobe. Internal margins of the valves contiguous at basal sixth; geni- 

 tal fissure quite broadly fusiform, and closed at basal half by the 

 inferior pudendal membrane. 



Ilahitat. — Southern California; Santa Catalina Island. 



Number of specimens studied, 500. 



Type is in the LeConte collection. 



Type-locality. — San Diego, California. 



Salient tyjye-cliaracters. — Longer than usual. Thorax slightly con- 

 vex, sides broadly rounded, somewhat narrowed posteriorly, finely 

 and sparsely punctulate. Elytra declivous and obliquely narrowed 

 behind, sparsely, finely, and very irregularly punctate. Femora un- 

 usually thick (LeConte). 



Diagnostic characters. — The most common species in Southern Cali- 

 fornia and always heretofore referred to qiiadricolUs., from Avhich it 

 differs in the smaller and more slender anterior spurs of the anterior 

 tibiae (females) ; from carhonaria., to which it is most closely related, 

 by the punctures of the elytral disc having a less distinct serial ar- 

 rangement, and by the serial punctures being scarcely larger than 

 those of the intervals, the tendency being toward diffuse punc- 

 tuation. 



Oniissa is with greater difficulty separated from the smooth form 

 of carhonaria., where the elytra punctures are small and of the same 

 size; here locality must be relied upon for their separation. All 

 those specimens from the eastern side of the Colorado River are 

 forms of carhonaria., while all those from the western side are to be 

 referred to the present species. 



I do not know of a single specimen taken west of the Colorado 

 River ever having been identified as an authentic carhonaria. In 

 fact I consider omissa as a western modification of carhonaria. 



07nis8a is a variable species in regard to the form of the pronotum, 

 but in the several hundreds Avliich I have studied I found an abun- 

 dance of all necessary mesotypes, both as regards the form of the 

 pronotum and elytral punctuation. 



In a large percentage of those individuals that have the sides of 

 the pronotum evenly arcuate from apex to base, it will be found 

 that they really present a more normal form of the side margin than 

 do those that are widest in front of the middle; for here it will be 

 seen that the sides of the pronotal disc are most strongly declivous 

 behind the middle and that the true margin is displaced downward 

 and not visible when the pronotum is viewed vertically from above; 



