MELOCRINID. 281 
ately concave; their upper corners but slightly truncated. First costals 
quadrangular, not more than half the size of the radials, a little wider than 
long, the lower face convex. Second costals nearly as large as the radials, 
their upper faces forming an obtuse angle. Distichals one in the calyx. 
Arms two to the ray; composed of rather stout quadrangular pieces. The 
two or three proximal free plates about as long as wide, the others compara- 
tively longer, and increasing in length upward. The pinnules, which are very 
stout, almost take the form of armlets; they are placed far apart, and their 
joints, like those of the arms, grow longer upwards. Interbrachials three 
preserved in the specimen, but having others above; the arrangement of the 
plates at the anal side unknown. Column of medium size; the joints 
rounded at their edges, and decreasing in height downward. 
Forizon and Locality.— Upper part of Trenton limestone; Trenton 
Falls, N. Y. 
Type in the Museum of Comparative Zotlogy, Cambridge. 
Remarks. — We refer this species with some doubt to Stedidiocrinus, which 
it approaches in its general characters; but as nothing is known of the struc- 
ture of its anal side, it may belong to a different genus, and perhaps to 
the Dolatocrinites. 
MARIACRINUS Hatt (emended W. and Sr.). 
1859. Hatt (in part) ; Paleont. N. Y., Vol. IIT, p. 104. 
1881. W. and Sp.; Revision Paleoer., Part IT., p. 114 (Proceed. Acad. Nat. Sci., Phila., p. 288). 
1885. W. and Sp.; Revision Paleoer., Part IIL., p. 104 (Proceed. Acad. Nat. Sci., Phila.. p. 326). 
1889. §S. A. Minter; N. Amer. Geol. and Paleont., p. 259. 
Calyx obconical, in general aspect resembling Glyptocrinus; interradial 
and interdistichal spaces large and more or less depressed ; the posterior 
interradius distinguished by having three plates in the second row; thie 
plates of the rays marked by a strong longitudinal ridge. 
Basals four, small, almost of uniform size. The one facing the anterior 
side a little the largest and pentangular, the others irregularly quadrangular. 
Radials and costals of similar size; costals two, the first hexagonal. Dis- 
tichals two to four. The palmars, of which generally the proximal plate 
only takes part in the calyx, support the arms. Arms composed of 
cuneiform pieces, which either remain simple, or give off a few branches 
to one side, Pinnules given off from opposite sides. Interbrachials rather 
numerous; anal side a little wider, and containing additional plates. Ventral 
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