ELATERIDAE. IT 3 



the rnesosternum declivous; the middle coxjb more conical and 

 prominent than usual, nearly contiguous ; the metasternum is very- 

 acute in front ; the coxal plates are dilated inwards, but not sud- 

 denly, and differ slightly in form in the respective genera ; they 

 .are toothed at the origin of the thighs. The tarsi are simple, 

 and pubescent beneath ; the claws are simple ; the tibial spurs 

 are more developed than in other tribes. 

 Two natural groups are obvious : — 



Front margined ; mandibles very prominent. Apheici. 



Front depressed ; mandibles not very prominent. Plastoceki. 



Group I.— Aphrici. 



Aphricus californicus, a small species having the appearance 

 of a slender Cardiophorus, is the only member of this group 

 known. The mandibles are long and slender, and project so as 

 to leave an open space between them and the front which is mar- 

 gined, and projects over the labrurn ; the antenna? are moderately 

 serrate ; the prosternum is very slightly lobecl ; the sutures are 

 single, and not excavated ; the middle coxae are prominent ; the 

 metasternum is obtuse in front ; the coxal plates are scarcely 

 toothed at the insertion of the thighs ; the first joint of the tarsi 

 is not longer than the second ; the sixth ventral segment is not 

 visible. 



Group II. — Plastoceri. 



The mandibles are thick at the base, toothed at the middle, 

 slender and curved at the tip, but embrace more or less closely 

 the labrurn, which is on the same plane with the depressed front, 

 and closely connected with it, almost as in certain Cebrionidos. 

 The antennae are long and serrate in Aplastus ; in the other ge- 

 nera short, and pectinate with long branches in the males, in the 

 females serrate, and slightly pectinate ; the prosternum is slightly 

 lobed in Aplastus, not at all lobed in the other genera ; the su- 

 tures are double, slightly oblique, and not excavated ; the middle 

 coxa? are prominent, with the rnesosternum acute in front ; the 

 coxal plates are gradually and sometimes strongly dilated in- 

 wards, and toothed at the origin of the thighs ; the first joint of 

 the tarsi is as long as the two following united ; the sixth ventral 

 segment projects beyond the fifth, which is round at the apex. In 

 the female of Euthysanius, however, the elytra are short, the 



