CANADIAN FOSSILS. 61 



Heterocrinus in^qualis, Billings. 



Plate IV. Figure la. 



Description. — Cup, pointed at the base; rays, large, rounded on 

 the back, and inequally divided. In the specimen figured, the two 

 first primary radial plates which can be seen are long and nearly 

 triangular, their lower acute angles meeting in the base of the cup 

 and their upper straight sides supporting free rays or arms. Only 

 three of the rays are visible in the specimen, the others being 

 imbedded in the matrix. One of these (partly shewn at the left side 

 of the figure,) appears to be simple or undivided .throughout. It is 

 nearly cylindrical, and consists of a series of large, transversely 

 oblong joints, one line and one fourth in width and two thirds of a 

 line in height. Its lower extremity is concealed, and I have not 

 been able therefore to ascertaia whether or not it originates in the 

 base of the cup. The central ray (of the figure) divides above the 

 third joint into two equal secondary rays, which are also several 

 times subdivided. In these subdivisions of the secondary rays, 

 however, the branches are of an unequal size, one of them in each 

 instance being about one-fourth the thickness of the other. The 

 other ray (partly exposed in the specimen,) is undivided from the 

 base to the fifth joint inclusive, above which it is buried in the stone. 

 The surface is minutely granular. 



I have placed this remarkable species in Heterocrinus provisionally, 

 as it most resembles species of that genus. When its structure 

 shall have been ascertained, it may be necessary to refer it to some 

 other genus. 



Locality and formation. — Trenton limestone, Ottawa. 



Heterocrinus articulosus, Billings. 

 Plate IV. Figure 8. 



Descripion. — Of this species we have only a single ray, which 

 much resembles one of the rays of H. incequalis, but is nevertheless 

 decidedly distinct. The secondary rays are irregularly jointed, the 

 plates where the branches are given off being broader than elsewhere. 

 In consequence of this character the rays have a peculiarly knotty 

 appearance. It is probable that this species and H. incequalis will, 

 when all their characters are known, constitute a new genus. 



Locality and formation. — Trenton limestone, Ottawa. 



