216 CALIFORNIA ACADEMY OF SCIENCES. 



associated with B. styliferus, but is remarkably distinct 

 from any in our fauna by the peculiar elytral sculpture. 



Chaetarthria. 



Three species of this genus are more or less plentiful 

 at almost any time of the year, by washing the sandy 

 margins of streams throughout Southern California, — 

 viz.: a pale form, C. 2^<^^ll^d(^(' Lee; a slightly larger, 

 piceous black species with pale legs and antennse, G. 

 nigrella Lee; and a smaller black species for which the 

 name G. minor is now proposed. It may always be 

 distinguished from G. nigrella by its distinctly smaller 

 size (1.2-1.5 mm. for C. minor and 1.6-2.2 mm. for G. 

 nigrella) and is moreover generally darker in color 

 throughout, this being especially noticeable of the legs 

 and antennae. The form is also a little less broad in G. 

 minor, the third joint from the last of the antennae is 

 smaller and more transverse, and the antennal club is 

 less elongate. 



A somewhat careful examination of our four species 

 shows that well defined specific characters are not easy 

 to find. It appears not to have been noticed that there 

 is a sexual difference in the form of the front tibiae. In 

 the females the tibiae are gradually broader to tip, while 

 in the males there is a distinct angulation on the inner 

 margin, beyond which the sides are parallel. In the 

 eastern G. atra the angulation is near the knee, while in 

 the Californian G. nigrella it is at or even a little beyond 

 the middle; otherwise these two species are very close. 

 In G. pallida the angle is less marked than in the two 

 preceding, but its position is nearly as in G. nigrella. 

 In G. minor the angle is not very obvious and is situated 

 at about the basal third. 



