276 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 



the plates somewhat smaller. Nothing is known of the ventral disk^ the 

 anal opening, and the upper portions of the arms. Column strong, round ; 

 composed of alternate thick and thin joints, all rounded along the edges, the 

 former twice as high as the latter, and somewhat wider. Axial canal large, 

 pentalobate. 



Horizon and Localitif. — Trenton limestone ; City of Ottawa, Canada. 



Remarhs. — This species has a superficial resemblance to certain species 

 of Archceocrinus, and in 1881 we referred it to that genus. But on examin- 

 ing the type specimen from the Canada Survey Museum we find it has no 

 infrabasals, and the angles of the axial canal are interradially disposed. 



(?) Glyptocrinus Fornshelli S. A. Miller. 

 Plate XX. Fig. S, and Plate XXL Fig. S. 



1874). S. A. Miller; Cincin. Quart. Joiirn. Sci., p. 348. 

 1881. W. and Sp. ; Revision Pal^eocr., Part II., p. 188. 



1883. S. A. MiLLEii; Journ. Cincin. Soc. Nat. Hist., Vol. VI., p. 227; and North Amer. Geol. and Paige- 

 ont., p. 248. 



Calyx elongate, obconical ; dorsal cup almost twice as high as wide, its 

 sides convex. Plates delicate and beautifully ornamented, being traversed 

 by sets of from five to seven small ridges, a set directed to each side of 

 the plate, and each set continued upon adjoining plates. The ridges of the 

 same set are parallel, those of different sets meeting at an angle at the 

 middle of the plates, and being so arranged as to form numerous rhombs, 

 each containing two sets of included triangles. Upon the radials and costals 

 the median ridge is but slightly stronger than the others, but on approach- 

 ing the distichals it enlarges rapidly, and at the fifth plate it attains the 

 proportions of an arm. 



Basals small, forming a short cup; the interbasal sutures deeply notched. 

 Radials and costals longer than wide, their upper and lower faces unusually 

 narrow ; the first costal somewhat longer than the radials, the second a little 

 smaller generally. Of the distichals, the ten to twelve lower plates take 

 part in the calyx ; the three proximal ones being but third smaller than 

 the costals ; the fourth is considerably shorter, and the succeeding ones 

 almost as short as the free brachials. Arms bifurcating (once or oftener), 

 long, very slender at their tips; constructed of moderately short, cuneate 

 pieces with stout and long pinnules. Interradial and interdistichal areas 

 elongate, and composed of an unusually large number of pieces ; the former 



