249 



the coast of South Carolina, have been kindly referred to me for 

 examination. Of these, two appear to be new. 



The first is included in the genus OpMothrix MuW. & Trosch., 

 and is allied to 0. angiilata, ( OpJiiura angulala Say) but differs 

 in the spines, the form of the ray-plates, &c. Its characters are 

 thus expressed. 



Ophiothrix HispiDA Ayres. 



Disk pentagonal, with the angles between the rays somewhat 

 prominent, about three tenths of an inch in diameter. Its entire 

 surface, excepting the plates above the insertion of the rays, is 

 thickly covered with spines, of different lengths, deeply dentate 

 both at the point and on the sides. Above the origin of each 

 ray is a pair of oval, naked plates, separated by a very narrow 

 line of spines ; their length is about one third of the diameter of 

 the disk. 



The 7^ays are a little more than an inch in length. The dorsal 

 plates are small, occupying only about a third of the breadth of 

 the ray. They are angularly ovate, with the broader end out- 

 ward, the narrower being concealed beneath the preceding scale. 

 The inferior plates are nearly square, separated from each other 

 by an intervening space. The lateral plates are larger, almost 

 meeting above. Their free border projects outward beyond the 

 base of the succeeding plate, so that the side of the ray appears 

 notched. Each supports five or six spines, longer than twice 

 the breadth of the ray, sharply dentate in their whole length, 

 pierced with numerous minute holes. The number of spines of 

 course diminishes toward the tip of the ray. The general ap- 

 pearance of the animal, from these long ray-spines and those of 

 the disk, suggests very readily the specific name Jiispida. 



The plates which separate the bases of the rays beneath are 

 small, broadly ovate. Those forming the border of the mouth 

 (Mundspalten) are oblong, with parallel sides destitute of teeth, 

 and terminate very abruptly. Each has a large oval foramen 

 near the outer extremity. 



Mr. Stimpson's specimen was obtained at Fort Johnson, in 

 shoal water. In the collection of the Society are two or three 

 others which were probably brought from the Tortugas by Mr. 



