CANADIAN FOSSILS. 



Genus Gltptocrinus, Hall. 



(Gltptoceinus, Hall, Paleontology of New York, Yolume i., page 280.) 



Formula : 



Basal plates, 5. 

 Radial plates, 3x5. 



Regular inter-radlals, 6. 

 Azygos inter-radials, 7 or more. 



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Fig. 18. 

 Figure 18. Diagram of the structure of the cup in the genus Glyptocrinus. 



Generic characters. — Cup, pyriform, globular or oval, in some spe- 

 cies very large ; arms, long, densely fringed with pinnulse ; base, 

 composed of five plates, which are either pentagonal or hexagonal ; 

 regular inter-radials, usually six; azygos inter-radials, seven or more ; 

 column, round or sub-pentagonal, strongly annulated or moniliform 

 in all the species known. 



The plates of the species of this genus are flat, thin, and either 

 smooth or ornamented with radiating ridges, striae or raised margins ; 

 the large joints of the columns are often nodulose. In the Black 

 River and Trenton limestones in Canada, the remains of several 

 species are exceedingly abundant, but usually reduced to mere frag- 

 ments of the plates and column. At the city of Ottawa, where these 



