60 CANADIAN FOSSILS. 



profusely ornaiiUBnted with radiating ridges and striae. Although 

 there is an abundance of the comminuted remains in the Chazy 

 limestone, yet only the base of the cup of one specimen has been 

 found. Fortunately it is sufficiently well-preserved to shew that at 

 least a great proportion of the numerous plates and columns with 

 which it was associated belong to the same species. The specimen 

 consists of four joints of the columns, two of the basal plates on "the 

 dorsal side, one large heptagonal plate of the second series, and 

 portions of two others, one on each side of this latter. The follow- 

 ing figure shows the disposition of the rhombs at the base of the 

 dorsal side : — 



At the base upon the dorsal side there are two perfect rhombs, 

 one-half of each of which is on the central basal plate ; the other two 

 halves are upon the two plates of the second series, which rest upon 

 the upper sloping sides of this basal plate. These two rhombs 

 therefore correspond to the pair occupying the same position in 

 Echino-encrinites angulosus, Volborth (see pi. iii. fig. lb), and G. mul- 

 tiporus, pi. iii. fig. la. In addition however, we have in G. Forhesi 

 two half-rhombs on two of the basal plates which do not occur in 

 the other species ; their positions are shewn in the above wood-cut. 



The plates have two sets of surface ridges : — 



1. From four to six large ridges, which radiate from the centre 

 of each plate to the centre of each straight side of the plate. They 

 are in general strongly elevated, with rounded or sharp edges and 

 broad bases. In the angular spaces formed by the large ridges 

 are smaller parallel ones, which form other included similar angular 

 spaces (see plate iii. figs. 3e and 2f). 



2. The whole surface of the plates is also covered with sharp 

 concentric striae, which are, on some of the plates, stronger between 

 the ridges than upon them (see plate iv. figs. 3e and 3fJ. When the 

 plates are worn, the large radiating ridges become rounded, and the 

 concentric striae are wholly obliterated. 



The joints of the column attached to the fragment figured appear 

 to be obscurely pentagonal ; but in the same rock are many columns 



