69 
considerably from those of the I. gigas; and the 
depth of the lateral lobes, which exceeds three-tenths 
of an inch, would almost of itself determine it to be 
a new species. The original, from which our cast 
was taken, is in the cabinet of J. P. Wetherill. It 
-was found near Newport, Kentucky, and occurs in 
argillaceous slate. The fossil is of a dirty yellow 
colour. 
Isoretus Cyctors.* Green. Cast No. 24. Fig. ae 
Clypeo antice attenuate, plano; oculis rotundis, 
proximis; cauda ovata, acuminata. 
- The head of this species is much more elongated 
than it is in the two preceding species. The anterior 
portion of the buckler is much prolonged. The eyes 
are approximate, rounded, and near the posterior 
edge of the head. The abdomen is furnished with 
eight distinct articulations; the middle lobe-is scarce- 
ly broader than the lateral lobes; tail rather broader 
than the head, and ovate; posterior termination more 
rounded than the buckier. Length nearly three inches. 
The specimen from which our model was taken 
belongs to the Albany Museum. No label is attach- 
ed to it, but I was informed by Mr. Meach, one of 
the proprietors, that it was found in the western part 
of the State of New York. It is embedded in an ash- 
coloured limestone. The specimen is a good deal 
worn—but the peculiar form of the eyes, and the nar- 
*From the Greek for “‘ round eyes.’’ 
