﻿Description of a Star Fish and other Fossils. 



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at least, were spine-bearing, though it would seem that there was not 

 more than one spine upon any single plate. The arrangement of the 

 plates on the dorsal side of the rays is very ornamental. A single 

 series of highly convex or conical plates, larger than the others, and 

 each evidently bearing a central spine, occupies the middle of each 

 ray; on either side near the margin of each ray there is a similar 

 series, and the two intervening spaces are filled with smaller, convex 

 plates, arranged in rows which are directed diagonally forward from 

 the plates of the side series to the plates of the central series, form- 

 ing angles with each plate in the central series occupying an angle. 

 This disposition of the plates on the dorsal side of the raj^s will, so 

 far as known, serve to distinguish this species from any hitherto 

 described. 



The plates covering the dorsal side of the body or disc have been 

 so much disturbed, in our specimen, that one can not correctly define 

 them. 



The ventral side is obscured by adhering earth in some parts, but 

 most of the characters can be ascertained. The ambulacral furrows 

 are wide. The marginal plates are hexagonal, about the size of the 

 larger plates on the dorsal side of the rays, and separated from the side 

 series by intervening smaller plates. Each bore several small spines, 

 as shown by the small pits for their articulation, beside some of them 

 are now preserved in our specimen. The spines upon the plates in 

 each axilla or junction of the rays are larger than those toward the 

 apices of the rays. 



The adambulacral plates are hexagonal and much wider than long. 

 They are more numerous than the marginal plates near the disc, but 

 toward the apices of the rays they alternately interlock with the mar- 

 ginal plates. The number on each side of a furrow in a complete ray 

 would be Mty or more. The pits for the articulation of the spines 

 are as numerous as they are on the marginal plates. These two series 

 on the ventral side of the species, with numerous spines upon each 

 plate, are in striking contrast with the plates on the dorsal side of 

 the rays, where no plate bears more than a single spine. 



The ambulacral plates have their greatest length across the rays, 

 and seem to be about as numerous as the adambulacral ones. An 

 angular depression marks the center of each ambulacral furrow, upou 

 each side of which a sharp ridge arises, upon each ambulacral plate, 

 and curving forward and outward abuts against an adambulacral plate. 

 The ambulacral, ossicles articulated upcm the commencement of the 



