1928] New Plastoceridce and a New Cebrio 145 
sternum and ventral segments more closely punctured, the ter- 
minal segment especially more densely so. The terminal segment 
is obliquely subsinuatelv narrowed through the greater part of 
its length, paler in color at apex which is narrowly subtruncate 
and clothed with more yellowish pubescence; it has a sub- 
marginal impression each side near the base. 
Length 6-8.2 mm.; width 1.4-1.75 mm. 
Described from a series of seven specimens taken in the 
Pinal Mts., Arizona, 5000 ft. (0. C. Poling collector). 
There are no obvious secondary sexual characters in the 
series at hand, but one example, from the exposed genitalia is 
certainly a male, and it is highly probable that all are of this sex. 
I am by no means entirely satisfied as to the propriety of 
referring this species to Aphricus, from the type (A. calif ornicus) 
of which it differs in the following respects. Tarsal joints 1-4 
decrease rapidly in length, the basal joint subequal to 2 and 3 
united and joint 2 subequal to 3 and 4 united; in Aphricus 
joints 1 and 2 are subequal while 3 and 4 are only slightly shorter. 
In the present species the side margins of the thorax are distinct 
and entire, in Aphricus they are in great part obliterated. In 
the present species the middle coxae are very narrowly separated 
and the metasternal process between them is very acute; in 
typical Aphricus the middle coxae are more widely separated, the 
metasterna] process wider and obtuse at tip. In this connection 
it should be remarked that the side margins of the prothorax 
may be either present or absent in Aplastus and that while 
Aphricus luteipennis agrees with calif ornicus in tarsal structure 
and non-margined thorax, it has the more approximate middle 
coxae and acute metasternal process of the present species. 
The mandibles in the present species are acute at tip nearly as 
in calif ornicus, but with the tooth of the inner margin less remote 
from the tip. The prosternal lobe is extremely short and obtusely 
rounded, the prosternal sutures nearly straight, single, and not 
excavate in front, the coxal plates scarcely toothed at the in- 
sertion of the thighs, and the sixth ventral segment not visible, 
all as in A. calif ornicus. 
