38 CALIFORNIA ACADEMY OF SCIENCES. 



capable of being flexed or straightened at pleasure, and, in 

 contradistinction to the former, such an antenna might be 

 called flexibly geniculate. 



Basal joint of tlie aiitenuae greatly elongated, sub-equal iu leugtli to tlie next 

 three or four together; antennae strongly and anteriorly geniculate. 



Neck broad Hesperobium. 



Neck narrow Ababactus. 



Basal joint of the antennae not greatly elongated; antennas posteriorly and 

 more or less strongly geniculate. 

 First four joints of the i)osterior tarsi sub-equal, first not longer than th8 

 second. 

 Neck rather broad. 



Prothorax sub-quadrate or slightly elongate; labrum bilobed 



Lathrobium. 



Prothorax narrowed from apex to base; labrum truncate, not dent- 

 iculate, having along the lower edge of its anterior margin four 

 widely-spaced, very short, broadly rounded callosities, and, in the 



middle a very small, rounded emargination Tr achy sect US. 



Neck very slender. 



Prothorax gradually narrowed anteriorly; labrum quadridentate. 



Scopaeus. 



Hind tarsi with the first four joints decreasing more or less gradually in 

 leugth. 

 Prothorax narrowed in front. 



Labrum quadridentate Echiaster. 



Labrum bidentate StilicUS. 



Prothorax sub-quadrate, anterior and posterior angles more or less nar- 

 rowly rounded. 

 Labrum having four rather large sub-equal teeth; elytra much longer 

 than the pronotum. 

 First joint of the posterior tarsi very slightly longer than the second. 



Orus. 



First joint of the posterior tarsi sub-equal in length to the next two 



together Caloderiiia. 



Labium with two pairs of minute approximate teeth; elytra no longer 



than the pronotum OllgoptcrUS. 



Labrum bidentate; elytra variable in leugth . Llthocharls. 



Labrum unidentate; elytra longer than the pronotum. Metaxyodonta. 

 Labrum rounded; acutely emar-inate at tip; elytra as long as the 



pronotum Dacnochllus. 



Labrum entire; elytra shorter than the pronotum.. . Llparocephalus. 



