38 



lobate lunate; the front is very convex, and a good 

 deal elevated above the cheeks or sides, from which 

 it is divided by a deep furrow; on the posterior mar- 

 gin of the front on each side, close to the groove there 

 is a prominent circular tubercle, before which there 

 are three small transverse wrinkles. The cheeks are 

 subtriangular; the oculiform tubercle is near the pos- 

 terior superior angle, and is only separated from the 

 tubercle on the front, by the furrow or groove, so that 

 the animal seems to have had double eyes on each 

 side; there are two curved lines on each side below 

 the eyes, crossed near the front by a deep short canal. 

 The middle lobe of the abdomen and tail is rather 

 longer than the lateral lobes, and is rounded and very 

 prominent throughout. It is composed of 18 articu- 

 lations, seven of which appear to belong to the tail; 

 it is, however, somewhat difficult to define the length 

 of the tail with precision. The costal arches of the 

 lateral lobes, particularly those near the tail, are 

 bifurcate. Length almost three inches. 



The original fossil, from which the cast was taken, 

 is in the New York Museum. I am indebted to Mr. 

 Rubens Peale, the liberal proprietor of that flourish- 

 ing and important institution, not only for the use of 

 it in this Monograph, but also for some valuable in- 

 formation relating to other species. The precise 

 locality of Mr. Peale's specimen is not known, but 

 in the cabinet of J. P. Wetherill, Esq., there is a fine 

 head of the C. diops which was found in the State of 

 Ohio. Both specimens are mineralized by the same 

 kind of soft grey coloured limestone and I have 



