26 COLEOPTERA OP NORTH AMERICA. 



I have combined Pristodactyla Dej. with Calathus, and Anchus 

 Lee. with Platynus, the differences becoming evanescent by the 

 comparison of many species. Colpodes should probably not be 

 separated from Platynus;* the characters are by no means distinct. 

 The species are quite numerous, and found under stones, mostly in 

 moist places. 



Our genera, as thus reduced, are as follows : — 



Tooth of the mentum emarginate ; ungues more or less serrate. 



Calathus. 

 Tooth of the mentum entire ; ungues simple ; 



Third joint of the antennae very long. Rhadine. 



Third joint of the antennae moderate ; 



Fourth joint of the tarsi emarginate, with long apical hairs, at least 



of the anterior pair. Colpodes. 



Fourth joint of the tarsi nearly entire. Platynus. 



Mentum without any tooth ; ungues simple. Olisthopus. 



Group II. — Pterostichi. 



The anterior tibiae are gradually thickened towards the apex, 

 and armed externally with small spines. The ungues are always 

 simple. The anterior tarsi of the male have the three dilated 

 joints triangular or cordate, sometimes (Loxandrus) oblique, as in 

 Galerita. The characters separating the genera are of but slight 

 importance, and in several (Lophoglossus, Holciophorus, and Lox- 

 andrus) depend upon sexual peculiarities of the male. Although 

 the species of Amara would never be confounded with Pterostichus 

 by a practised eye, there is no difference capable of being used in 

 a synoptic table for the purpose of distinguishing the two genera. 

 For this reason the assemblage of characters common to all species 

 of Amara, but which are only individually present in some species 

 of Pterostichus, must be used. They are given below. According 

 to the latest researches, Pcecilus cannot be retained separate from 

 Pterostichus. 



Mentum tooth emarginate, last joint of palpi dilated. Myas. 



Mentum tooth emarginate, last joint of palpi cylindrical (rarely oval) ; 

 Episterna of metathorax short ; elytra with one dorsal puncture ; pro- 

 sternum not margined, but channelled. Evartheus. 



* This genus is called Anchomenus by most foreign authors. I have 

 detailed in other places the reasons which induce me to retain the name 

 here adopted. 



