182 



PAL-EONTOLOGY OF NEW-YORK. 



JOINTS OF UNDETERMINED CRINOIDEA. 



Pl. a XLT. Figs. 7 o - e. 



These bodies, from their structure, are apparently the joints of crinoidal columns, "which have 

 been worn smooth, and the marginal angles worn down to a rounded edge : the canal is also 

 rounded and enlarged, and the whole presents a flattened globular appearance with a depression 

 in the centre. When these bodies are separated from the stone, the two sides are precisely 

 similar. They vary in thickness from half an inch to the fiftieth part of an inch. The thicker 

 ones are mostly found in the iron ore, and appear not so much worn as macerated and dissolved. 

 They present in fact the same peculiar oolitic aspect with the materials of the iron ore, where 

 all the little fragments of fossils, of whatever kind, have lost their angular character. In the 

 shale at Sodus and other places there are many thin joints of this kind, which are clearly worn 

 or dissolved away on the prominent edges and angles, and they all present the smooth uniform 

 character peculiar to the thicker ones in the iron ore. Some of these appear to be composed of 

 more than one joint or articulation, but so closely united that there is no line of separation except 

 upon the edge. All these are crystalline in structure, and those in ore are replaced by crystallized 

 carbonate of iron. 



In their external aspect the rings have lost all the characteristic features of the Crinoidea, 

 but their crystalline structure is a clearly distinctive character on which we can rely. 



Fig. 7 a. One of these rings, presenting a smooth globular surface, with a smooth opening in the 

 centre. The thickness of this one is nearly a quarter of an inch. 



Fig. 7 b. The impression left in the iron ore by a larger individual, the thickness of which was 

 more than a quarter of an inch. 



Fig. 7 c. A very thick one, with a small opening in the centre. 



Fig. 7 d. A small specimen of the same character. 



Fig. 7 e. View of the edge of a very thin specimen. 



Position and locality. All the specimens figured are from the iron ores south of Mohawk 

 village, on Steele's creek. Similar specimens, but smaller and thinner, occur in the shales of the 

 lower part of the group in Wayne county. {State Collection.) 



576. 1. CARYOCRINUS ORNATUS. 



Pl. a XLI. Fig. 1. 



For description, see this species under Niagara group. 



The only specimen known in the Clinton group, presents the anomalous structure shown in 



the figure referred to. The difference between this structure and the structure usually found 



in tliis species is clearly shown by a comparison with the figure on Plate 49. The difference in 



■ this one appears to result from the modification or imperfect development of the second series 



of plates, and the absence in part of the third series or scapular plates, allowing the arms to 



