1 C0LE0PTERA OF NORTH AMERICA. 



though it should separate genera so similar in sculpture as Opis- 

 thius and Elaphrus. 



The sculpture of the elytra is very variable ; sometimes (Xebria) 

 the striae have the normal number (nine), usually, however, they 

 are more numerous ; in Notiophilus the inner striae are separated 

 from the outer ones by a very wide smooth space ; in Opisthius 

 the sculpture consists of rows of shallow ocellate fovea?; in certain 

 species of Cychrus and Carabus the elytra are ornamented with 

 rows of tubercles. 



Our genera may be thus arranged: — 



A. Head triangular ; prosternum prolonged behind the anterior coxae ; 



epipleurae narrow. 



a. Mentum bidentate ; 



Anterior tibiae obliquely truncate. Notiophilus. 



Anterior tibiae with both spurs terminal ; elytra with ocellate 



foveae. Opisthius. 



Elytra with nine striae, the outer one frequently obliterated ; 



(inner spur of anterior tibiae not quite terminal) ; 

 Maxillae armed beneath with bristles. Nebria. 



Maxillae armed beneath with spines. Leistus. 



b. Mentum tooth simple (elytra with numerous striae) ; 



Third joint of antennae strongly compressed. Calosoma. 



Third joint of antennae cylindrical. Carabus. 



B. Head elongate ; labrum deeply bilobed ; epipleurse very broad. 



Antennae with two glabrous joints; striae of the elytra not exceeding 

 thirteen. Nomaretus. 



Antennae with four glabrous joints ; striae of the elytra numerous, 

 sometimes replaced by tubercles. Cychrus. 



Of these genera, Opisthius contains a single species, found in 

 Oregon and at Mackenzie River; Leistus one species from Russian 

 America, and is also found in Europe. Nomaretus is confined to 

 the Atlantic slope; the other genera are widely diffused. 



Tribe VI.-METRIIIVI. 



This tribe contains but a single Californian species (Metrius 

 contractus Esch.), of singular form, found under stones in forests. 

 The head somewhat obtuse, the clypeal suture transverse, the 

 eyes small, not prominent; the mandibles are trigonal, concave 

 externally, as in most Carabida?; the antenna? have four glabrous 

 joints. The mentum is deeply emarginate, with a bifid tooth; 

 gular suture distinct; palpi moderately stout. Anterior coxae en- 



