290 COLEOPTERA OF NORTH AMERICA. 



abdomen is as long as the two following in C. denlalus, but 

 equal to the three following in C. scatnbu^. 



The differences above noted indicate the necessity of separating 

 C. scambus as a distinct genus for which the name riectromerus 

 J^Dej. may be adopted. 



Tribe IV.— OBRIIIVI. 



A tribe containing only small species, which are easily distin- 

 guished by the front coxa) being more prominent than usual, 

 sometimes nearly conical, and frequently contiguous, but com- 

 pletely inclosed behind. The pal})i are usually slender, rarely 

 with the last joint triangular. The other characters arc abnor- 

 mal, the abdomen in the 9 being deformed in the group Obria, 

 and the elytra more or less subulate or abbreviated in Stenopteri; 

 the eyes are finely granulated in the latter, variable in the former. 



The affinities of this tribe lead from the last groups of Ceram- 

 bycini, towards the tril)es with finely granulated eyes, Lepturini 

 on the one side, and Callidiini on the other. 



Group I. — Obria. 



This group contains a few small species in which the granula- 

 tion of the eyes has ceased to be of primary importance; but 

 which is easily distinguished by the 1st segment of the abdomen 

 being very long, and the 2d and following irregular, hairy, ex- 

 cavated or deformed in the 9 . 



The mandii)]es are small and acute, the antennse slender, as 

 long as, or shorter than, the body; the palpi are unequal, and the 

 last joint is rarely dilated. The antennae are slender, and the 

 2d joint is larger than in genuine Cerambycini. The prothorax 

 is variable in form, always, however, constricted and peduncu- 

 lated at base, and narrower than the elytra; the front coxae are 

 conical, prominent, contiguous, cavities small, rounded or angu- 

 lated, closed behind; middle coXal cavities not open extenmlly. 

 'The thighs are Strongly clavate, the tibial spurs small or mode- 

 rate, and the 1st joint of the hind tarsi is as long as the two 

 ifollowing. 



It is worthy of remark that in Obrium the structure of the eyes 

 has merely specific significance; in our 0. rvhrinn the eyes are 

 ■very coarsely granulated, while in the nearly allied European 0. 

 ibrunneum the lenses are much smaller. 



