CANADIAN FOSSILS. 59 



Explanation op Figures. Plates VII. and VIII. 



Plate 7, figure 2a. A cup of medium size. 



" 26. Portion of the column near the base of the cup. 



" 2c-2/. These figures represent different parts of a very long column. 

 Plate 8, figure la. A crushed specimen, with part of the column attached. 



" 16. The column of la, enlarged. 



" Ic, Id. Columns found along with la. 



Locality and formation. — Trenton limestone, City of Ottawa, Island 

 of St. Joseph, in Lake Huron. 



Gltptocrinus marginatus, Billings. 

 Plate IX. Figure la. 



(G. maeginatus, Report Geological Survey of Canada^ 1856, page 260.) 



Description. — The plates of this fine species are all margined by a 

 strong elevated border, the effect of which is to give to the surface 

 a beautifully reticulated appearance. The only specimen in the 

 collection is crushed, but then the size of the plates near the bottom 

 shows that it had a broad, rounded base, and that its general form 

 was sub-globular. The azygos inter-radial space contains ten plates 

 below the level of the base of the secondary rays ; the rays are all 

 carinated, and there is also an upright row of small plates (in the 

 centre of the azygos inter-radial space) which exhibits a faint keel. 

 There are four or five of the secondary radial plates included in the 

 cup. A piece of the column two inches and a half in length remains 

 attached, and shows that the large joints at the base of the cup of 

 this species were much thicker, and consequently not so sharp-edged 

 as those occupying a similar position in the other species. 



The length of this cup from the base to the free arms is one inch 

 and a half, and the breadth about the same. The column is four 

 lines in diameter, and in the length of two inches and a half there 

 are twenty-one large joints with the same number of others a little 

 smaller, each situated half way between two of the largest. The 

 arms are not preserved in the specimen. 



This species also grew to a large size, and was closely related to 

 both G. priscus and G. ramulosus. 



Explanation of Figures. Plate IX. 

 Figure la. View of the only specimen collected. 



Locality and formation. — Trenton limestone. City of Ottawa. 



