Col eopl etiological Notices, VI. 609 



slightly move than twice as long as wide. In one respect riversi 

 differs from all the other members of this genus, the female being 

 more densely and conspicuoiislj^ clothed than the male ; it is pos- 

 sible, however, in spite of general facies, that this female does not 

 really belong to the same species, especially' as the basal angles of 

 the prothorax are broadly rounded. The hairs are much finer 

 than usual. 



The two examples in my cabinet were kindly communicated by 

 Mr! J. J. Rivers, who possesses a considerable series. 



These species should Ijoth be placed between ca^yenteri and 

 squamicoUis in the table previously published b}- me (Col. Not. 



I, p. no). 



It is impossible to properly associate the males and females in 

 this genus unless they be collected at the same time and place, 

 and it is consequently seldom prudent to base a species upon the 

 female alone. 



XYLORYCTES Hope. 



X. fauiius n. sp. — Moderately stout, strongly convex, polished, Llack 

 throughout above, dark red-brown beneath, the tibise and tarsi somewhat 

 piceous in tinge; under surface clothed with long brownish-red hair, the upper 

 surface and pygidium glabrous. 



31ale — Head less than one-third as wide as the prothorax, the clypeal apex 

 reflexed and bilobed; dorsal horn nearly in satyrus but shorter. Prothorax 

 three-fourths Avider than long, widest near the middle, the sides rounded, 

 strongly convergent, anteriorly; discal declivity beginning at the middle when 

 viewed from above, deep, somewhat excavatetl, it posterior margin prominent 

 but rounded in the middle, its surface covered sparsely with transversely sul)- 

 crescentiform punctures, the posterior elevated surface coarsely and densely 

 punctured anteriorly' at the sides. Elytra nearly as long as wide, equal in 

 width to the prothorax and twice as long, obsoletely striato-punctate. Pygid- 

 ium two and one-half times as Avide as long. 



Female — Scarcely at all narrower than the male, the head nearly as in safy- 

 rns. Prothorax two-thirds wider than long, evenly convex but feebly im- 

 pressed and more densely and roughly punctured near each apical angle; sides 

 evenly convergent and broadly arcuate from near the base, the basal angles 

 broadly rounded. Elytra very nearly as long as wide, more deeply striate than 

 in the male, the pygidium more canaliculate along the lower margin. 



Length 28.0-30.0 nun.; width 15.0 mm. 



Arizona. 



This species differs from satyrus in its narrower and more 

 ■elongate form. The male differs from the corresponding sex of 

 satyrus in having the vertical wall of the thoracic depression 



