142 GEO. H. HORN, M. D. 



what little value these organs have in the formation of tribes and groups 

 of genera. The ligula of OHsthopus is very plainly that of many Lebiides, 

 Platijnus reproduces very closely that of Pterosticlius, Calathus proper 

 is as nearly as possible intermediate between the two while the section 

 Pristodactt/la is a modification of Flatynus. The tip of the ligula is free 

 in Platynus and Pristodactyla and not free in the other genera. 



The mentum tooth also seems to furnish characters of an evanescent 

 nature. In some Platynus^ especially those in which the hind angles of 

 the thorax are distinct {brunneomarginatus, ovipennis, etc.), the tooth 

 is longitudinally impressed and emarginate at tip, while in the Ayonum 

 type the tooth is very obtuse. The same variation is observed in Calathus, 

 some having quite an acute tooth, others even bifid. 



The tribe seems to be divisible primarily into three groups by the 

 following characters : 



Eighth elytral stria distant from the margin and not deeply impressed. 



Thorax truncate or emarginate at base Platyni. 



Thorax slightly lobed at middle of base Masoref. 



Eighth elytral stria confluent with the margin in its basal half, deeply impressed 

 and attaiiiing the suture Perigoni. 



Group Platyni. 

 This group might easily be separated in many minor subdivisions by 

 including the genera not represented in our fauna. 

 The following genera occur with us : 



Ungues more or less serrate. Mentum toothed. 



Tarsi glabrous above. Elytra with dorsal punctures Calatliiis. 



Tarsi hairy above. Elytra without dorsal punctures Pristonycliiis. 



Ungues not serrate. Elytra with dorsal punctures. 



Mentum toothed Platynus. 



Mentum not toothed Olistliopus. 



OHsthopus is represented in the Atlantic region by two species, the 

 other genera occur on both sides of the continent. Of Pristom/chus 

 two species are known both of them identical with European forms 

 (complunatus and terricola), and have probably been introduced, the first 

 mentioned being rather widely spread by commerce over the globe. 



Anchus Lee, founded on Plutynus pusillus is not distinct from Platy- 

 nus. The species is our equivalent for Anchomenus ohlongulus Fab., 

 of Europe, and may even be specifically identical, the only striking diflfer- 

 ence between the two being in the slightly wider thorax of our species. 



To this group I would refer Wollaston's genus Zargm. The facies 

 of the species is not unlike that of certain of our Platynvs {stria tits, 

 snJcatus). The clypeus is membranous at middle even to a greater 

 extent than in DIcrochik while the labrum is also bifid. Chaudoir is 



