60 CANADIAN FOSSILS. 



Glyptocrinus ornatus, Billings. 

 Plate IX. Figure 2a. 



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



Description. — In the specimens of this species that have been 

 collected the cup is broad-oval, the base well rounded, but narrovrer 

 than the upper extremity; the rays (as in the other species) are 

 keeled, and there are ten long, slender, undivided free arras, as in 

 G. priscus. Each of the plates is ornamented with five or six sharp 

 ridges, which radiate from the centre, thus covering the body with 

 numerous stars with triangular interspaces. The column is round, 

 and the large joints are thin, sharp-edged, and distant from each 

 other half a line at and near the base of the cup in a specimen of 

 the ordinary size. 



Length of the cup in several specimens, a little more than half 

 an inch ; diameter at the base of the free rays, about the same ; 

 diameter of column at the base of the cup, about one line. 



The surface ornament of this species is very like that of G. 

 decadactyhs (Hall) of the Hudson River group ; but there is a very 

 decided difference in the foraa of the columns of the two. Those 

 figured by Professor Hall have the large joints very thick and 

 rounded, while in G. ornatus they are exceedingly thin and sharp- 

 edged ; some of our specimens are very like the figure of G. basalis 

 (McCoy), given on page 180 of Sir Roderick Murchison's Siluria, 

 1st edition. In Sedgwick and McCoy's British Palaeozoic Rocks, 

 (p. 57) however, that species is described by Prof. McCoy as having 

 the pelvic plate immediately below the large inter-radial space, 

 hexagonal, and supporting upon its upper truncated margin the 

 large inter-radial. In our species all the pelvic plates are very 

 small and pentagonal. To both the English and New York species 

 ours is evidently closely allied. 



Explanation of Figures. Plate IX. 

 Figure 2a. Anterior side of a specimen of G. ornatus. 



Locality and formation. — Upper half of the Trenton limestone, 

 City of Ottawa. 



