. 
a - i ra * = 4 ——— —— — — — 
ee 
672 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
Platycrinus graphicus Hatz and Warr. 
Plate LXXI. Fig. 7. 
1863. Hatt and WuitTrretD; 17th Rep. N. Y. State Cab. Nat. Hist., p. 55; and 1875, Geol. Surv. Ohio 
Vol. II., Part I1., p. 166, Plate 1], Fig. 2. 
1881. W. and Sv.; Revision, Part II., p. 72 (Proceed. Acad. Nat. Sci. Phila., p. 246). 
Syn. P. richfieldensis Haun and Wurtr.; 1875, Geol. Surv. of Ohio, Vol. IL., Part II., p. 167, Plate 
Ty, Wess he 
Below medium size. The known specimens of this species are badly 
crushed, and it is impossible to give the form and proportions of the calyx, 
but probably the dorsal cup was moderately short and rounded at the base. 
The plates are thin and without ornamentation. 
Basal cup apparently deep, its height being probably equal to half the 
length of the radials. Radials wider than long, subquadrangular, thickened 
in the middle, the upper faces of the limbs very slightly sloping, and but 
little excavated tor the facet, which faces upwards, and occupies half the 
width of the plate. Costals rather large, the upper angle sharply pointed, 
the upper sloping faces distinctly concave. Distichals free from their origin, 
considerably narrower than the costals, a little longer than wide. Arms four 
to the ray, rather delicate, the four or five lower joints wedge-form and | 
alternately arranged, the succeeding ones arranged in two series and sub- 
quadrangular; all joints moderately long. The pinnules in adult specimens | 
in contact laterally. Structure of ventral disk unknown. Column joints 
nearly circular, angular around their edges. The column is composed of 
rather long joints, which alternate with shorter ones, from which we infer | 
that this species possessed internodal joints. | 
Horizon and Locahty.— Shales of the Waverly group, Richfield, Summit 
Co., Ohio. | 
Type in the New York State Cabinet at Albany. 
Lemarks.— The specimen figured by Hall and Whitfield as P. richfiel- 
densis undoubtedly represents an immature specimen of P. graphicus. The | 
authors admit the strong resemblance of the two forms, but separate them : 
upon the arm structure. They described the arms of P. richfieldensis as 
being “composed of a double series of obtusely wedge-form plates in the 
lower [upper] part,* the sharp or narrow edges of which extend nearly 
* The description says “lower part,” which obviously is meant for upper part, and “upper part” in the 
next line for /ower part. 
rT Se 
