112 
GEOLOGY OF THE FOURTH DISTRICT. 
1, 2. Caryocrinus ornatus (Say, Jour. Acad. Nat. Sci. Yol. 4, p.289). — This fossil 
usually occurs separated from the column, and destitute of arms or tentacula. From its sphe¬ 
roidal form, it has received the name of “ Petrified Walnut .” It is composed of plates which 
are tuberculated on the surface, having generally a double row of larger ones along the line 
from the centre to each angle of the plate. The dark lines in the figures indicate the junction 
of the plates. The points of attachment of the arms are visible near the top of the specimen. 
Fig. 2 is a view of the base, presenting the point of attachment of the column, the form of the 
pelvic plates, and the bases of the costals. Separate plates are often met with, and they may 
always be known by their strongly tuberculated surface. 
This fossil occurs in great numbers at Lockport, and in many instances covered by a coral 
which had grown upon it after the destruction of the former, as is evident from its often co¬ 
vering the point of attachment of the column and arms, and closing up the aperture on the 
crown. 
The C. loricatus of Say, was probably a specimen which had undergone some modifica¬ 
tion in the form of the plates, from injury or otherwise, a circumstance apparently not un¬ 
common among the Crinoidea. 
Locality —Lockport, and more rarely at Rochester and Sweden. 
3. Cyathocrinites pyriformis (Silurian Researches, p. 672, pi. 17, f. 6. Ichthyocrinus 
Icevis, Conrad, Jour. Acad. Nat. Sci. Vol. 8, p. 279, pi. 15, f. 16.) — This species is known 
by the great width of the plates near the base, which unite laterally, and divide in ascending 
until they form the arm divisions ; the latter fold inward toward the centre, sometimes nearly 
closing. The upper part of the column is very slender, and composed of thin plates, which 
join by a suture formed by the elevated lines which radiate from the centre. The surface is 
faintly ornamented. 
From the many specimens seen, which vary in form and proportions to a considerable de¬ 
gree, I have no doubt of the identity of the fossils figured by Mr. Murchison and Mr. Conrad. 
Locality —Lockport. 
