18 THE ACRIDIIDAE OF MINNESOTA 
horizontal carina extending from the principal sulcus to the posterior 
margin; their anterior and posterior borders are oblique and their 
lower margin nearly straight. Prosternal tubercle absent. Tegmina 
usually shorter than the abdomen in the female although in a specimen 
now before us they extend considerably beyond the tip of the abdomen. 
This genus is represented in North America by but one species. 
Opeia obscura Thom. 
Opeia obscura is, in general, western in distribution but we have 
taken it at Brown Valley, Fergus Falls, and Mankato. It is extremely 
variable, particularly in coloration. In typical forms the dorsum is 
green or brown and nearly plain, although sometimes more or less 
distinctly streaked with fuscous along the median carina. The sides 
are marked by a stripe extending backward from the eye, largely dark 
upon the head but widening and becoming more obscure posteriorly. 
This stripe consists, upon the pronotum, of five parts as follows: An 
upper streak of brownish or fuscous below the lateral carina; below 
this a somewhat broader light or greenish streak, followed by a white 
line on the prozonal lobe, which is continued as a white, raised, nearly 
horizontal carina across the metazonal lobe; below this a dark streak 
similar to the upper one and this followed below by another light or 
whitish streak. Bruner, speaking of this species, says “it occurs 
where the grasses are short and the climate arid,’ but in all cases 
where it has yet been taken in this State, it has been found in damp 
or marshy places amid tall grasses and Carices. The following meas- 
urements are from a female, taken at Fergus Falls: length 19.5 mm., 
tegmina 14.5 mm., and hind femur 11.5 mm. 
ERITETTIX. Bruner 
Head more or less conical, occiput not elevated, furnished with 
three carinae, one median and two supplementary. The median carina 
extends from the pronotum to the tip of vertex where it becomes 
enlarged, the supplementary from the pronotum to a point opposite 
the anterior margin of the eye where they are each abruptly deflected 
to join the lateral carinae of the vertex, thus marking off the vertex 
into an equilateral triangle. Foveolae are shallow and triangular, not 
visible from above. Frontal costa has the sides regularly divergent 
from the vertex to the clypeus, generally a little constricted above the 
ocellus and slightly sulcate for a greater or less distance above this 
but never sulcate to the vertex. The antennae are thick, generally 
somewhat flattened at the base, and clavate at the apex, which is bluntly 
