84 
PALEONTOLOGY OF NEW-YORK. 
124. 2. POTERIOCRINUS GRACILIS. 
Pl. XXVIII. Figs. 2 a, b, c, d, e,f. 
Body small, obconical, gradually expanding above, surmounted by long slender bi¬ 
furcating tentacula, which are not fimbriated. 
The pelvic and costal plates are precisely in form like those of the last species, but the 
brachial plate is much shorter, and but five-sided ; the attachment of the fingers upon the 
upper side is by a broad plate. The surface of the plates is finely granulated, appearing 
nearly smooth to the naked eye. The fingers are thrice bifurcated above the hand-joints, 
and, towards their termination, appear to be covered by a muscular integument. The column 
is proportionally much larger than in the last species, and is composed of thin even plates, 
which are closely adhering at the margins, and sometimes appear striated longitudinally, 
the whole presenting an appearance as if covered by an integument. A few of the upper 
joints of the column, only, have been seen in a single specimen ; the last joint adheres 
closely to the base of the pelvis. This species differs, likewise, in the much greater length 
of the tentacula, which are somewhat unequally bifurcated above, and composed of long 
smooth joints, while in the previous species the fingers are tentaculated and shorter. 
The irregular intercostal (interscapular of Miller) plate is distinguishable in this species, 
showing that it is clearly referable to this genus. 
Fig. 2 a. A specimen of the natural size, which is broken off just below the last joint of the column, 
which adheres closely to the pelvis. The tentacula are broken off above, before reaching 
their termination. 
Fig. 2 b. The same enlarged, showing more clearly the arragement of the plates, and the situation of 
the intercostal plate. 
e. Pelvis. 
f. Costal plates. 
j. Irregular intercostal plate. 
h. Scapular plate. 
Fig. 2 e. The body of another specimen, with a few of the last joints of the column attached. 
Fig. 2 d. The same enlarged, showing the intercostal plate and the structure of the column. 
Position and locality. This species has been found only in the soft shaly layers near the 
base of the Trenton limestone, at Middleville, Herkimer county. 
(From the Collections of Mr. Wadleigh and Dr. Emmons.) 
