250 COLEOPTERA OF NORTH AMERICA. 



Group III. — Orchesiae. 



Head vertically deflexed ; antennae gradually thickened exter- 

 nally, 11-jointed, third joint not conspicuously elongated ; maxil- 

 lary palpi with the last joint more or less dilated ; anterior coxae 

 oval, separated by the prosternum; middle coxae separated; hind 

 coxae contiguous, flat, variable in form, oblicpae in Hallomenus, 

 not oblique in the other genera ; spurs of middle and hind tibiae 

 variable in size, but very large and serrate in Orchesia ; tarsi 

 filiform ; claws simple. 



Hind coxae small ; tibial spurs long, simple. Eustrophus. 



Hind coxa? large ; tibial spurs serrate. Okchesia. 



Hind coxae oblique ; tibial spurs simple. Hallomenus. 



One species of Eustrophus was found by me at the Colorado 

 and Gila Rivers of California, and one of Hallomenus is known 

 from Russian America ; the other species are found in the 

 Atlantic States. 



Group IV. — Serropalpi. 



Head more or less inclined, sometimes vertical ; frontal suture 

 not distinct ; antennae variable, third joint not conspicuously 

 elongated ; maxillary palpi variable, sometimes very long, with 

 the third and fourth joints dilated internally, and the fourth large 

 and securiform (in which case they are called serriform) ; ante- 

 rior coxae conical, contiguous, without trochantin, except in 

 Xylita, where the trochantin is indistinct ; middle coxae not con- 

 tiguous, except in Xylita ; tibial spurs slender, sometimes very 

 small ; tarsi with penultimate joint sometimes emarginate or lobed ; 

 claws simple. 



I have united into one group the Serropalpides and a portion 

 of the Melandryides, of Lacordaire, as they seem insensibly to 

 merge together. 



Our genera may be thus tabulated : — 



Hind tarsi with 3d and 4th joints equal ; palpi strongly serriform. 



Serropalpus. 

 Hind tarsi with 3d joint shorter than the 4th, more or less lobed. 

 Maxillary palpi with the second and third joints as wide as the 4th ; 

 Head vertical ; prosternum short in front of coxae. Dirc jea ? 



Head oblique ; prosternum not very short ; 



Maxillary palpi not serriform. Phloiotrya ? 



Maxillary palpi serriform. Hypulus. 



