174 Psyche [December 
more slender than in the female, longer than the supra-anal plate at middle. Legs 
and antennz longer than in the female, the latter as long as the body. 
Nymph: Similar to female, lighter in color. The suture on the front of head is 
more distinct than in the adult. 
Described from one male and numerous females and nymphs 
taken at Guerrero Mill in nests of Formica subcyanea Wheeler, 
F. rufibarbis Fab. var. gnava Buckley, and Camponotus maculatus 
Fab. subsp. picipes Olivier. Some of the females had odthece 
attached. They were abundant, several occurring in almost 
every nest, where they are no doubt very efficient scavengers. 
The genus has no systematic affinities with Attaphila, the only 
other known Blattid of Myrmecophilous habits, but is more 
closely related to Blatta, to which it runs in Caudell’s key to the 
genera of this family (Proc. U. S. Nat. Mus. Vol. 44, 1913, 
p. 601-602). 
COLEOPTERA. 
Family STAPHYLINID®. 
Pseudolomechusa subgen. nov. 
Type: Xenodusa sharpt Wasmann. 
This beetle was described by Wasmann from a series which 
were taken at Cuernavaca, in company with Camponotus auricomus 
Roger. In one canyon near the Guerrero Mill I found a number of 
adults, some of them in copula, with colonies of Camponotus 
maculatus var. picipes, Olivier which was here very abundant. 
In the immediate vicinity were many nests of Formica microgyna 
rasilis var. nahua Wheeler and several of T. rufibarbis var. gnava. 
Buckley. With the former ant three adults of sharpi were taken and 
with gnava several more, and three larvee, the latter close to the 
ant brood. As most of the beetles were found with C. prcipes 
(nineteen were taken from one nest) it appears that this is the 
secondary or winter host and F. gnava the primary or definitive. 
This heterocious habit is common to all of our species of Xenodusa 
as faras known. The adult sharpi is very different from the other 
American species on account of its greatly thickened pronotal_ 
margins and shorter antennal joints. Seen in profile the anterior 
border is drawn out beneath into a distinct angle similar to the 
structure in the species of the European genus Lomechusa. 
