58 | 
visible, exhibiting concentric strie. They hole 
face of the animal has a jet black polish. pene 
from 6 to 12 inches. ey ee 
_ The original of our cast is in the cabinet of J. P. 
Wetherill, and was found near Cincinnati, Ohio. It is 
of a yellowish colour, and occurs in argillaceous slate. 
Specimens are common in most cabinets of Ameri- 
can fossils. The Lyceum in New York, possesses a 
fragment of an individual of this species, which must 
have been at least 17 inches long.. Our cast, No. 22, 
is from the gigantic tail in the cabinet of P. A. Brown, 
Esq. Mr. Stokes describes the I. gigas as a new 
species under the name of Asaphus Platycephalus, in 
Geolog. Trans. vol. i. N. Series. His specimen was 
found in 1 the limestone of St. Joseph’s, Canada. 
~ Tsorenus Pianus-* Dekay. Cast No.28. 
Head more rounded than the preceding, and less 
elevated. Tail flat, rounded. Total length two inch- 
es and one-tenth. Breadth one inch and one-tenth. 
Length of the head, six-tenths—of the abdonieay ig 
eight-tenths, and of the tail seven-tenths, = = 
Dr. Dekay is of opinion that this species may pos- 
sibly prove to be the young of the preceding. © The 
relative proportions of its pe and tail vary 
wis ig Bae. Re ot 
* The general usage of Prorat ate is. to prefix a short ‘Latin 
caption to the species which they discover—but as some anthors 
do not follow this fashion, we are satisfied to suffer r their dese leser. 
tions to stand without it. We believe, indeed, that ‘ue SO. 
not very distant, when every author will be cece. to oblieb . 
peer 
his discoveries in his vernacular tongue. 
