218 MEMOIRS ON THE COLEOPTERA 



lobe sparsely punctate, not beaded at apex; mesosternal sinus broad and 

 very shallow; arcuate hind tibiae but slightly thickened distally, the 

 anterior with five small sharp subequal serrulations. Length 4.7 mm.; 

 width 3.35 mm. California (locality unrecorded), McBride. 



This species is allied to umbilicatus, also a native of California in 

 the vicinity of San Francisco, but it differs in its less elongate-oval 

 form, more transverse prothorax, unmargined prosternal lobe and 

 less definitely limited sinus of the mesosternum; the prosternal 

 beading is very distinct in umbilicatus. From the Oregonian um- 

 brosus, it differs in its much shorter prothorax and elytra and less 

 definite mesosternal sinus. Umbrosus differs from umbiUcatus in 

 its unmargined prosternal lobe and also in the very much denser 

 pygidial sculpture; I have recently received a good series taken by 

 Moznette at Corvallis, Oregon. 



Group Abbreviatus. 



The species ccenosus Er., is one of the most widely distributed, 

 the material in my collection showing that it extends, practically 

 without variation, from North Carolina to Arizona and Durango. 

 The outer edge of the anterior tibiae is minutely and evenly multi- 

 serrulate. In the following species the general characters are 

 nearly as in ccenosus, but there are numerous differences as may be 

 noted : 



*Hister opacicauda n. sp. Similar in form and color to ccenosus but not 

 quite so broadly oval, convex, shining, the pygidia opaculate, having a 

 ground sculpture of fine and irregularly wavy strigilation; head with the 

 frontal stria feebly interrupted, the surface of the front smooth but 

 feebly concave; prothorax nearly as in ccenosus throughout, the inner 

 stria parallel to the edge but rather less removed therefrom; elytra 

 similar in every way, except that the striae are not quite so coarse, the 

 fourth discal being notably fine and almost obliterated, more distinct 

 toward base and apex, and that the humeral stria bifurcates just before 

 the middle, the upper ramus very short, the lower, representing the sub- 

 humeral, extending to basal fourth; pygidia finely, sparsely punctured, 

 nearly as in ccenosus, the propygidium less transverse; under surface and 

 legs nearly similar, except that the outer apical angle of the anterior 

 tibiae is less broadly rounded and the outer edge throughout smooth and 

 without serrulation. Length 6.8 mm.; width 4.7 mm. Mexico (Cuer- 

 navaca). The collector unrecorded. 



It is possible that the fine tibial serrulation characterizing ccenosus, 

 may have become worn off in the single example serving as the type, 

 but in this case it is not easily conceivable why the outer angle 



