40 [April, 



cies upon which Bonelli formed his three genera, Platynus, Anehomenus, and 

 Agonum. My reason for preferring for this assemblage of species the name 

 Platynus, is merely, that such was the name chosen by Mr. Brulle, who was 

 the first entomologist to perceive the necessity of merging the groups into one 

 genus. Two years afterwards, Erichson proposed to call the assemblage of 

 Bonelli's three genera by the name Anehomenus, alleging that Platynus was in- 

 applicable to most of the species, and that it had, moreover, been employed (in 

 the form Platyna) for a genus of Diptera ; the first point, in the present state of 

 nomenclature, need not occupy our attention; the second point is also without 

 weight, since Platyna was proposed as a genus many years after the establish- 

 ment of Platynus by Bonelli, and before it was shown that the latter genus in- 

 cluded any other form than that to which it was limited by the author. The 

 name Platynus was consequently not vacant, and its application in any form, to 

 a genus other than that intended by Bonelli was improper. 



This genus, as here understood, contains a very large number of species, all 

 agreeing in having the paraglossae scarcely longer than the ligula ; the mentum 

 tooth distinct and not emarginate ; the palpi slender, with the last joint ahout 

 equal to the preceding; the first joint of the antennae moderately thick, not 

 longer than the third, which again is not longer than the fourth; the tarsi are 

 filiform, and the ungues entirely smooth. 



The antennas are usually filiform, but sometimes setaceous. The form of body 

 is variable, usually somewhat slender, with the elytra nearly twice as wide as 

 the head or thorax, and oval or oblong, sometimes elliptical ; the elytra are 

 either rounded, truncate or emarginate at the base, usually slightly sinuate at 

 the apex, and sometimes almost truncate, in which case a form of body results 

 not unlike Dromius or Metabletus. Occasionally the form of body is stouter, 

 and the elytra are hardly one half wider than the thorax ; and in some west- 

 ern species, unknown to me, the form is said to be almost similar to Calathus ; 

 these latter species have been separated by Motschulsky as Tanystoma, (after- 

 wards changed to Tanystola) ; the only characters given are, that the last joint of 

 the palpi is longer than the preceding, and the posterior angles of the thorax ob- 

 tuse. Scaphiodactylus (Chaudoir) is also said to have the palpi as in Tanystola, 

 but the posterior angles of the thorax are acute. Not having identified these 

 genera, I can with propriety say nothing in regard to them. 



The thorax is very variable in form, being sometimes oval, sometimes cordate, 

 square, or rounded ; the margin is sometimes strongly reflexed, sometimes hardly 

 visible. The interval between the second and third stria; of the elytra is always 

 marked with punctures, or fovae, varying in number from three to seven ; some 

 species, not known to me by personal observation, are described as having but 

 two punctures. 



To facilitate the determination of our species, the following division into 

 groups may be found useful. 



A. Corpus apterum gracile ; thorax fortiter marginatus, ovalis ; elytra humeris 

 rotundatis indistinctis. Sp. 1 4. 



B. Corpus alatum gracile ; thorax margine mediocri, elytra basi truncata, an- 

 gulis posticis distinctis, tripunctata. 



a. Angulis posticis thoracis non prominulis ; antennae subsetaceae ; 

 tenuiter striata. Sp. 5 7- 



b. Angulis posticis thoracis prominulis; antennas filiformes ; elytra tenuiter 

 striata. Sp. 8 9. 



c. Nigerrimi ; elytra profunde striata. Sp. 10 11. 



C. Corpus alatum, gracile ; thorax subcordatus, tenuiter marginatus, angulis 

 posticis distinctis, impressionibus basalibus proecipue profundis productis. 



d. Elytra tripunctata, pedes concolores. Sp. 12 13. 



e. Elytra multipunctata, pedes run, vel picei. Sp. 14 18. 



D. Corpus alatum, praecipue minus gracile, thorax rotundatus, (raro quadratus;) 

 lytra tripunctata. 



f. Praecipue nigri (raro picei vel metallici ;) pedes concolores. Sp. 19 31. 



