196 COLEOPTERA OP NORTH AMERICA. 



Eyes finely granulated ; 



Labrum entire. Tillus. 



Labruni emarginate, posterior thighs elongated. Perilypus. 



Eyes coarsely granulated. Cymatodeka. 



Elasmocerus inhabits the Atlantic district, Cymatodera is widely 

 diffused, the representatives of the other genera are unknown to 

 me. Tillus collaris is found in Georgia, and Perilypus is said to 

 be from California. 



Group II.— Cleri. 



Head large, eyes not very prominent, emarginate in front ; mid- 

 dle coxae rounded, slightly prominent ; tarsi with the first joint 

 much shorter than the second, and covered by it, so as not to be 

 visible from above ; the species are more numerous than in the 

 other groups. 



Eyes strongly granulated. 



Antennae serrate, maxillary palpi cylindrical. Prioceea. 



Antennse with the joints 9 — 11 larger; all the palpi dilated. 



Tarsostenps. 

 Eyes finely granulated. 



Maxillary palpi somewhat dilated, antennal club triangular. 



Trichodes. 

 Maxillary palpi not dilated ; 



Posterior tarsi short, not dilated. Thaneroclerus. 



Posterior tarsi moderate, broadly dilated. Clerus. 

 Posterior tarsi longer, scarcely dilated ; 



Body hairy, opake. Thanasimcts. 



Body less hairy, shining. Cleronomus. 



The last genus, identical with Colyphus Spinola, is unknown 

 to me, the species are said to be from California ; the characters 

 are declared by Lacordaire to be very similar to those of Thanasi- 

 mus, but the appearance of the species is very different. 



Trichodes and Clerus are widely extended ; the other genera 

 are reoresented only in the Atlantic district. 



Group III. — Hydnoceri. 



Head large, eyes very prominent, entire ; middle coxa? not 

 prominent, slightly separated ; tarsi with the first joint shorter than 

 the second, principally inferior ; maxillary palpi cylindrical. 



But one genus of this group, Hydnocera, exists in our fauna. 

 It is widely diffused ; the species are small, and have the form of 

 Cicindela ; they are found on leaves of trees, and are active, taking 



