166 Trans. Acad. Sci. of St. Louis. 



The described species noted in the above table were pre- 

 viously regarded by the writer as forming ' ' Group A " of 

 Lithocharis (Bull. Cal. Acad. Sci., II, 1886), but are evi- 

 dently congeneric with the European Medon . The species de- 

 scribed under the names inquilinum, nitidulum and opaculum 

 are apparently associated with ants, or, at least, the first 

 is pinned with some specimens of a small piceous-black ant, 

 having dark brown legs and antennae and 2.2 mm. in length; 

 all three of them are probably rare and are represented at 

 present by unique females. Americanum is also represented 

 by a single female, the male being apparently much rarer 

 than the female throughout the genus. 



Parainedon n. gen. 



This genus is composed of a large number of species con- 

 fined principally to the true Pacific coast fauna but extending 

 also into the adjacent elevated regions of the continent, hav- 

 ing, in fact, a distribution almost precisely similar to that of 

 Orus, of the Scopaei. It is closely allied to Medon, but has 

 the anterior tarsi much more strongly dilated, especially in 

 the male, and the male sexual characters are of a different 

 character; in external appearance it differs in its rather 

 stouter form with relatively larger elytra. In a previous paper 

 by the author describing a few of the species (Bull. Cal. Acad. 

 Sci., II, 1886), it was erroneously regarded as a section of 

 Lithocharis. The species resemble each other to such a 

 degree that it seems to be impossible to separate them in a 

 recognizable manner by descriptions, without making exten- 

 sive use of the secondary male sexual characters, which con- 

 spicuously modify the apex of the fifth ventral segment; 

 these are fortunately sufficiently varied to enable us to do 

 this with greater or less success. The large rounded einargi- 

 nation of the sixth ventral is, however, so constant in form 

 as to be of very little use in classification. The gular sutures 

 vary greatly in extent of separation, from almost complete 

 contiguity, as in Jcernianum, to a very wide degree of separa- 

 tion, as in gulare. This enables us to divide the species into 



