4 MEMOIRS ON THE COLEOPTERA. 



Gyronycha of the Hygronomini, Oxypoda of the Aleocharini Co- 

 prothassa of the Myrmedoniini and so on in many other cases. 

 A question might arise therefore, as to whether subdivisions based 

 on tarsal structure are entirely natural. This I cannot venture to 

 determine at present and can only state that it is the most con- 

 venient system that has been devised, with a very great probability 

 that the recurrent resemblances above noted in part are merely 

 accidental adaptations to similar general environmental conditions, 

 or due to common elements in the environment or habits, and are 

 in no way essentially phylogenetic in significance. This being 

 assumed, it seems evident that the heterogeneity of the tarsi in 

 the genera allied to Myllcena, the three genera Myllcena, Deinopsis 

 and Gymnusa having divergencies among themselves in tarsal 

 characters nearly similar to those serving to define tribes in the 

 Aleocharinse proper, indicates that these three genera should 

 constitute a subfamily equivalent in value to the Aleocharinae 

 or Tachyporinse, between which their structure as well as general 

 habitus undoubtedly places them. 



The species described in the present paper are all confined to 

 North America, north of the Mexican boundary, excepting Alo- 

 conota flexibilis, Hydrosmecta depresseola and Nosora azteca, which 

 form part of the fauna of Mexico. 



Subfamily ALEOCHARINI 

 Tribe ALEOCHARINI. 



Baryodma Thorns. 



The species placed under this heading in my revision of the genus 

 (Tr. Ac. St. Louis, XVI, p. 150 et seq.), seem to comprise some 

 groups which have received special names in the European fauna, 

 such as Coprochara Rey., but at present I do not perceive enough 

 structural diversity to warrant more than a single name. The 

 three following species are to be placed near insulana Csy. : 



Baryodma rubricalis n. sp. Rather stout and convex, subparallel, 

 shining, black, the legs blackish-piceous, the elytra entirely rufous; 

 punctures moderately fine, everywhere sparse, except on the elytra where 

 they are stronger, asperate and closer; pubescence rather long and coarse 

 but sparse, subochreous though not conspicuous; head two-thirds as 

 wide as the prothorax, the antennae deep black, rather short, stout, 



