32 CANADIAN FOSSILS. 



Carabocrinus Vancortlandti, Billiogs. 

 Plate II. Figure 4. 



Description. — Of this fine and rare species only one spscimen has 

 been seen, and thit is unfortunately so much injured on the anterior 

 side that the arrangement of the azygos phites cannot be determined. 

 The form of the body is rather broad oval, the height being fifteen 

 lines from the base to the margin, while the greatest diameter near 

 the centre of the body is twelve lines. The base is narrowly 

 rounded, and the cup expands gradually for about half the height, 

 above which it contracts to the margin, where the width is about 

 one line less than it is at the centre. The height of the posterior 

 basal plate is five lines and a half, its greatest width four lines: the 

 hexagonal basal, five lines high and about the same in width. Of 

 the sub-radials, three are well-preserved ; they are slightly narrower 

 below than above. Height of the sub-radials, eight lines; width 

 between the two upper lateral angles, seven lines, and between the 

 two lower, five lines. The primary radials are each six and a half 

 lines wide and five lines high. The arms are rounded on the back, 

 and a little more than one line in thickness. They have each three 

 single joints, the third being pentagonal and supporting upon its 

 upper sloping sides two secondary rays, which are subdivided at 

 the distance of two lines and a half. 



The surface is ornamented with radiating ridges, as in C. radiatus ; 

 but the ridges are proportionally smaller and more distant from 

 each other. 



This species is clearly distinct from C, radiatus, from which it 

 differs in being of an oval instead of a subglobular shape. In all the 

 specimens of C. radiatus the width is greater than the height ; while 

 in C. Vancortlandti the height is greater than the width. It is also 

 to be observed, that in the former the arms divide above the second 

 free joint, and in the latter above the third. 



The species is dedicated to Dr. E. Vancortlandt, of the City of 

 Ottawa, whose zeal in the advancement of science has been produc- 

 tive of many beneficial results. The only specimen known belongs 

 to his cabinet, and has been kindly communicated by him to us for 

 description. 



Explanation of Figures. Plate II. 

 Figure 4 exhibits a view of the posterior side of the specimen. 



Locality and formation. — Trenton limestone ; Township of McNab, 

 near Arnprior. 



