135 



of the tide. It prefers regions covered with eel-grass {Zostera) 

 but confines itself entirely to sandy bottonas. I have studied its 

 habits chiefly at Sag Harbor, Long Island, where it is abundant. 

 It is found near to Sclerodactyla briareus Le S. but not in 

 company with it, that choosing the mud and this the sand for a 

 residence. And so marked is the preference that in certain 

 localities ,. the two animals live in great numbers within three 

 yards of each other and yet neither ever encroaches upon the 

 other's territory. It manifests very little disposition to dismem- 

 ber itself on beins; handled. 



The disc, which is generally quite flattened, attains sometimes 

 a diameter of seven tenths of an inch. It is covered with small 

 spines or granules closely set over its whole surface, so that no 

 plates are visible. When these granules, however, are removed, 

 the disc is seen to be formed of minute plates, as in the previous 

 species, (O. rohusta.) Of the pair of plates, so often found at 

 the base of each ray, no trace can here be discerned, even under 

 a magnifier. 



The length of the rays exceeds four times the diameter of the 

 disc. The superior ray-plates are transversely elongated ; the 

 inferior are small, rounded ; the lateral bear six to eight short, 

 blunt spines, which, notwithstanding their number, are so incon- 

 spicuous as to detract very little from the smoothness of the ray. 



The granules of the disc cover also the inferior inter-brachial 

 spaces, in each of which the two pairs of genital openings are 

 well marked. The inter-brachial plates are very regularly ovate. 

 The plates forming the angles of the mouth bear fifteen to 

 eighteen teeth. 



Mr. Ayres also presented a cast of the new species of 

 Star-fish exhibited by him at the previous meeting, in 

 Gutta Percha. This was the first application, he said, so 

 far as he knew, of this substance to such a purpose, and it 

 made a much better cast than gypsum, bringing out many 

 points which that would not exhibit at all, and being of 

 great strength and durability. He presented the casts in 

 the name of Mrs. Westfall, of Sag Harbor, to whom the So- 

 ciety was indebted for the use of the original specimen. 



