358 THE CKINOIDEA CAMEKATA OF NORTH AMERICA. 



the lower side of the spine there is but one ridge, which leads to the basals. 

 The ridges upon the first interbrachials cuhninate in a sharp node in the 

 centre. 



Basals comparatively small, occupying but half the depth of the con- 

 . cavity. Eadials very large, the lower half curving abruptly- inward, and 

 forming a sharp edge upon which the cup rests. Costals very small, the 

 two together less than half the .size of the radiuls ; the first from two to 

 three times as wide as long ; the second a very little higher and truncated at 

 the top. Distichals, palmars, and interdistichals very small ; the first inter- 

 brachial unusually large, and as wide as long. Ventral disk stout, and to 

 the base of the tube twice as high as the doi'sal cup ; the sides rising verti- 

 cally to the top of the trigonal plate of the first ring, whence they slope 

 slightly to the summit of the ten larger ones, and more rapidly to the tube, 

 which near its base is moderately thick. The ten larger plates of the first 

 ring are longer than the whole dorsal cup, the intervening trigonal ones but 

 half as long. The former, as seen from gutta percha impressions, have long 

 spiniform appendages, which probably resembled those of CalUcrinus murcki- 

 soniauus Angelin (Iconogr. Plate 28, Fig. 14) ; the}^ are a little compressed 

 at the sides, and are directed upwards and outwards. The trigonal pieces 

 also rise into spiniform partitions, but these are shorter and smaller gener- 

 ally. Structure of the arms unknown. 



Horizon and Locality. — Niagara group ; Racine, Wise, and Chicago, Ills. 



T//2)es in the N. Y. State Cabinet of Natural History at Albany. 



Remarks. — The large collections of Mr. Thomas A. Greene of Milwaukee, 

 and Mr. W. C Egan of Chicago, contain a few specimens in which the dor- 

 sal cup is unusually expanded at the arm bases, less broadly truncated at 

 the bottom, and the first costals somewhat larger ; while otherwise agreeing 

 with the rest of the specimens. These specimens do not agree with C. cor- 

 nntus, var. excavafiis Hall, which was not accepted by Whitfield, and we think 

 that both these forms may be regarded as variations of C. cornutus. 



(?) Callicrinus ramifer F. Eoemek. 



I860. Eiicali/ptocrinus ramifer — Koe5IEII Silur. Fauna West. Tenn., p. 51, Plate 4, Figs. 4(7, b, c. 

 1885. Eucalyptocrinus ramifei — W. and Sp. ; Revision Palreocr., Part III., p. 13 i. 



This species is only known from the general form of its dorsal cup, and 

 there is some doubt whether it .should be referred to Cnllicrinus or to a new 

 genus. It differs from the other species of that genus in the size of its has- 



