56 CANADIAN FOSSILS. 



rocks are exposed on a large scale, three of the species hereinafter 

 described, G. priscus, G. ramulosus, and G. marginaWs, appear to be 

 more common than at any other locality yet examined. The heads 

 are frequently found there in a fragmentary state, but good speci- 

 mens are rare. G. priscus is the only head collected in the Black 

 River limestone, but it also occurs in the Trenton. I have met M^ith 

 G. lacunosus near the top of the Trenton limestone only. G. ornatus 

 is found about the middle of the deposit, rather common, and in 

 fewer numbers upv^;^ards to the Utica slate. There is a sixth species 

 u'hicli also occurs at Ottawa, but is only known by its very charac- 

 teristic sub-pentagonal column. 



Gltptocrinus peiscus, Billings. 

 Plate VII. Figures la-]/. 



(G. PRISCUS, Report Geological Survey of Canada, 1856, page 28Y.) 



Bcscriiition. — The cup of this species is pretty regularly oval, 

 covered with smooth plates and surmounted by ten long undivided 

 fingers or free rays, which are densely fringed with two rows of 

 pinnulae. A strong rounded carina, or ridge, runs up each of the 

 primary rays, and, dividing into two upon the centre of the third 

 plate, sends a branch up each of the secondary rays to the base of 

 the fingers ; the carinas are also divided upon each of the basal plates, 

 and coalesce into one on the centres of the first primary radial plates ; 

 in the azygos inter-radius a sixth ridge ascends to the top of the 

 cup, dividing the space into two parts about equal ; it bifurcates 

 below on the centre of the large azygos, one branch proceeding to 

 the centre of each of the two contiguous first primary radial plates. 

 The basal plates are of a moderate size, but the first radials are large, 

 broad, and in contact with each other by their upright lateral 

 margins. The joints of the free rays are thin and very closely set. 

 The rays are also rather broadly rounded on the back. As to the 

 column, the only perfect head in the collection has but a single joint 

 attached to its base, but the columns found associated with it and 

 also those which have been observed in the Trenton limestone afc 

 Ottawa, along with the fragments of the heads of individuals of this 

 species, are round, with the large joints rather thick and rather 

 nodulose. I think this species grew to a very large size ; but the 

 evidence is not sufficient to connect positively the small specimen 



