10 COLEOPTERA OF NORTH AMERICA. 



Calosoma ; with us the latter genus lias the greater number of 

 species but the disparity between the genera is not so great as in 

 Europe. 



Tribe v.— KLAPHRIXI. 



Antennae moderate in length, rarely longer than head and 

 thorax, tliree basal joints glabrous, the fourth pubescent at tip or 

 entirely glabrous in Diachila, base free, a slight ridge in BlethUa. 

 Eyes' round, usually prominent, moderately distant from the buc- 

 cal fissure. Front more or less deflexed, with two supra-or))ital 

 setce. Labrum moderate, truncate. Mandililes stuut, concave 

 externally, with a setigerous puncture, arcuate, acute at tip. 

 Maxillae hooked at tij), ciliate or spinulose externally, outer lobe 

 slender, biarticulate ; palpi moderate in length, terminal joint 

 longer than the preceding. Mentnin emarginate with a bifid or 

 emarginate tooth, ligula free at tip, bisetose, acute in Ela})hrus, 

 broad in the other genera, paraglossae slender, longer than the 

 ligula, the palpi moderate, the last two joints equal, the penulti- 

 mate bisetose in front, except in Diachila. Thorax variable in 

 form, the seta in the posterior angle always present, the lateral 

 absent in most Elaphrus. Body not pedunculate, scutellum 

 distinct. Elytra not margined at base except feebly near the 

 humeri in Blcthisa, sides narrowly inflexed, margin entire. Pro- 

 sternum obtuse at tip not prolonged behind the coxae, the coxal 

 cavities closed. Mesosternum not prominent. Metasternal epi- 

 mera not distinct, the posterior coxae contiguous. Legs moderate. 

 Middle and posterior tibiae slightly spinulose externally, the ante- 

 rior obliquely grooved, the inner spur above the apex. Tarsi 

 slender. 



The genera are separated in the following manner: — 



Men-turn tooth large, nearly as long as the lateral lobes, emarginate. 

 Thorax without lateral seta. Elytra witlx variolate foveae, not striate. 



Elaphrus. 

 Mentum tooth short, bifid at tip. Thorax with lateral setigerous puncture. 

 Head not sulcate, elytra with feeble strife of punctiires. Diachila. 



Head with deep lateral grooves, elytra striate with interstrial f(ive;e. 



Blethisa. 



Elaphrus. — The affinities existing between this genus and 

 OpiKthius will be referred to in the proper place. It is remark- 

 able that the lateral seta of the thorax is absent in all the species 



