18 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



and contrasting sharply with the remaining portion; antennae orange- 

 brown, paler proximally and on distal article; venter dusky yellowish 

 brown, the caudal segments tending to reddish. 



Head of same form as in adult. 



Dorsal plates as in small adults or nearly so; the ninth and eleventh 

 plates obliquely excised much as in the adult fulvicornis, but the 

 oblique line relatively shorter. 



Prosternal teeth 3+3, small, pale, with the outer on each side 

 minute; proportions of prosternum as in the adult. 



Antennae composed of 26 to 28, but mostly of 27, articles; in a 

 minor number of specimens subdivision of one or of two of these 

 articles is weakly indicated. 



Coxal pores 2, 2, 2, 2. 



Gonopods nearly as in adult; claw a little more curved; basal 

 spines stout, conical, the outer proportionately wider at base than in 

 adult, the inner relatively more slender than in adult but not so much 

 shorter as usual in this stage in Lithobii. Bristles nearly fully devel- 

 oped. 



Length 6-6.5 mm. 



LOCALITIES: Nevada (Las Vegas!); California (ClaremontI). 



BUETHOBIUS Chamberlin. 

 Ann. Ent. soc. America, 1911, 4, p. 34. 



Labrum deeply incised as usual at middle; tooth conical and 

 strongly chitinized; lateral divisions with border each side of the in- 

 cision bent abruptly dorsad, strongly chitinized, and weakly notched 

 at mesocaudal angle in such a way as to leave there a small and at 

 times nearly obscure blunt tooth-like process apparently homologous 

 with the lateral tooth in Lithobius, etc.; edge of lateral divisions 

 bearing long plumose hairs of which those at the mesal end of the 

 series are distally laciniate and are longest and also bearing simple 

 hairs in an area each side of the mesal incision. (Plate 3, fig. 6). 



Mandibles bearing four dentate divisions of plate of which the one 

 at end opposite the aciculi is simple and conical the other three being 

 set obliquely and each tridentate with the middle tooth longest and 

 the one toward convex surface smallest (see Plate 3, fig. 3); bearing 

 at caudal corner of distal end a row of ten to twelve large, flattened, 

 acute aciculi which are bipectinate over the distal portion and also 

 ectad of these and the teeth a series of finer plumose bristles. 



