HOMALIIDAE. 319 



Lahnim entirely liorny ; maxillary lobes short, mem- 

 branous ; second joint of maxillary palpi longer than third, 

 fourth rather shorter than second and third together. Fore- 

 head bordered, slightly impressed ; thorax as broad as 

 elytra; tibiae with spines. Acidota, Leach. 



2* First and second joints of posterior tarsi about 

 equal in length. 



A A, Tibiae without spines. 



a a. Head not constricted behind, forehead 

 not bordered. 



Maxillary lobes elongate, horny ; last joint of maxillary 

 palpi rather longer than second and nearly double as long- 

 as third. Forehead almost even, ocelli doul)le as far from 

 each other as from eyes ; thorax about as broad as elytra, 

 whicli are wide and long. Olo])hrum, Er. 



J) h. Head constricted behind ; forehead bor- 

 dered. 



Maxillary lobes membranous, inner one smaller, outer 

 one much dilated toward apex ; last joint of maxillary 

 palpi longer than second and more than double as long as 

 third ; ligula with anterior margin hairy. Forehead slightly 

 impressed ; thorax as broad as elytra, which cover the 

 greater part of abdomen. Lathrimaeum, Er. 



S S. Tibiae with spines. 



Maxillary lobes as in Lathriviaeum, but inner one 

 scarcely so small ; last joint of maxillary palpi about 

 double as long as third ; ligula with anterior margin not 

 hairy. Forehead not bordered in front, with shallow im- 

 pressions ; elytra covering greater part of abdomen. 



Deli2ihrum, Er. 



IV, Mandibles short, one of them with one tooth in 

 middle, the other without any. 



Maxillary lobes membranous, not very short, outer one 

 not dilated ; second joint of maxillary palpi rather longer 

 than third and rather shorter than fourth. Antennae 

 slender, all joints much longer than broad ; forehead not 

 bordered, with a short longitudinal furrow before ocelli ; 

 thorax rather narrower than elytra ; tibiae without spines, 

 first three joints of posterior tarsi gradually sliorter. 



Arjjediatii, Er. 



