1927] 
The North American Species of Rybaxis 
221 
rounded posteriorly; dorsal abdominal carinse separated 
at base by slightly less, and at apex by very nearly one- 
third the discal width of the segment clavata. 
Metasternal processes posterior in position 7 
7. Ventral plate of male very strongly transverse, typically 
fully three times as wide as long; dorsal abdominal car- 
inse separated even at base by distinctly more than one- 
third the discal width of the segment transversa. 
Ventral plate of male very small, more or less rounded behind, 
truncate in front, a little variable but usually about as 
long as wide; dorsal abdominal carinse separated at base 
by slightly less than one third the discal segmental 
width . .mystica. 
8. Metasternal processes of male anterior in position, widely 
separated, strongly developed and acuminate; dorsal ab- 
dominal carinse separated at apex by one-third the discal 
segmental width varicornis. 
Metasternal processes anterior, short, closely approximate, 
and blunt at. tip ; dorsal abdominal carinse separated at 
apex by one-fourth the discal segmental width. gemina ta. 
Metasternal processes posterior, feeble, being merely obtuse 
tumidities; dorsal abdominal carinse separated by only 
about one-fifth the discal segmental width arkansana. 
Rybaxis valida Brendel. 
This species is our only one haying the median pronotal 
fovea pubescent and is instantly recognizable thereby. The an- 
tennse are rather slender, all joints, including those of the club, 
longer than wide, the latter not modified in the male. The 
dorsal abdominal carinse are plainly more widely separated than 
one-third the discal width of the segment. The ventral plate, in 
the single male at hand in which it can be seen, is quadrate and 
slightly wider than long. The male front trochanters appear to 
be unarmed. The size is slightly larger than in any of our other 
species. 
Described from New York and Illinois; specimens before me 
are from the latter state. 
