174 CALIFORNIA ACADEMY OF SCIENCES. [18] 



dentate or prominent externally at apex; teuth auteuual joint finely tuber- 

 culate, eleventh with a short, erect arcuate process at base, both projecting 

 internally. 



Female. — Abdomen, trochanters aud antennae normal; terminal process of 

 posterior tibiae long, slender and contorted. Body smaller, more slender. 



The fimicle of the antenna is remarkably constant in 

 structure throughout the series, but the last four joints differ 

 in shape and relative size. 



In this group the head is not materially modified in the 

 male, so that it differs greatly from a large and important 

 group of eastern species. From a direct comparison with 

 B. formicarius Aube, the type of Batrisus, it is probable that 

 these species should be separated as a subgenus; this has 

 apparently been already done by Eeitter under the name 

 Batrisodes. 



The type of the European Batrisus is found, as its name 

 implies, with ants; the Calif ornian species are never found 

 in such localities, but are to be met with only in wet moss 

 or under stones near water-courses; although widely diffused, 

 they are scarely ever abundant, and are generally extremely 

 rare. 



B. mendocino n. sp. — Moderately robust, convex, dark brownish-rufous; 

 legs same; abdomen and antennae darker, castaueous, the latter pale toward 

 apex; integuments 2Jolished; pubescence coarse, rather long, suberect, rather 

 sparse. Head moderate, scarcely as wide as long; eyes rather small, very 

 convex, prominent, at more th in their own length from the base ; sides behind 

 them strongly convergent aud arcuate to the neck, which is slightly less than 

 one-half as wide as the width at the eyes, very feebly sinuate; surface impunc- 

 tate, slightly convex; on a line through the posterior limits of the eyes there 

 are two distinct, deeply impressed fovea?, apparently nude, connected by a 

 deeply impressed, strongly and evenly arcuate channel; antennal tubercula- 

 tions broad and prominent; antennae rather slender, distinctly longer than 

 the head aud prothorax together, club slender; basal j lint rather robust, 

 scarcely longer than wide, apex deeply notched posteriorly for the reception 

 of the second joint when flexed; joints two to five equal, slightly longer than 

 wide, sixth and seventh equal, slightly smaller, longer than wide, eighth as 

 wide as the seventh, rounded, as wide as long, eighth to eleventh gradually 

 wider, ninth and tenth equal in length, the latter much more strongly trans- 

 verse, eleventh elougate, conoidal, pointed. Prothorax widest at two-fifths 

 the length from the apex, where it is as wide as the head, slightly wider than 



