INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 503 



On the bottoms of loose siliceous saDcl tlie Uchinarachnius parma (p. 

 302, Plate XXXV, fig. 267) is often very abundant. Several hundred are 

 sometimes obtained at a single cast of the dredge. At locality 81, h, 

 off the south coast of Martha's Vineyard, in 21 fathoms, on a bottom of 

 clear siliceous sand. Dr. A. S. Packard dredged a fine specimen of a 

 rare and little known Holothurian, the Stereodernia unisemita. This has 

 not been found before, so far as known to me, since the two original 

 specimens were described twenty years ago. One of those was from the 

 Banks of Newfoundland, and tbe other was supposed to have been from 

 off Massachusetts Bay. As both the original specimens appear to have 

 been lost or destroyed, this rediscovery w^as of considerable interest. 

 This specimen was about three inches long, and half an inch in diam- 

 eter, fusiform, tapering to each endj the body and suckers were pale 

 flesh-color, and the integument is filled with a great abundance of small 

 calcareous pl^rtes. 



Most of the Polyps and Sponges that occur on these sandy bot- 

 toms are attached to the scattering dead shells and small stones or 

 pebbles, and belong properly on the rocky and stony bottoms. One 

 large and fine sponge seems, however, to be peculiar to the sandy 

 bottoms. This is a firm, siliceous sponge, with a very compact and fine 

 texture. It is quite irregular in shape, but often grows in the form of 

 elongated, compressed masses, attached by one edge -, these masses are 

 often six inches or more in length and one or two in thickness, and 

 perhaps two or three high. Some of the largest specimens consist of 

 two or three such crest-like plates or lobes attached together at base. 

 When living the colons bright sulphur-yellow or lemon-yellow, and the 

 surface is nearly smooth. One fine living specimen, of large size, was 

 dredged b^- Dr. Packard off the southern shore of Martha's Vineyard, at 

 locality 80, h, on a bottom of clear siliceous sand. Numerous specimens 

 were also found thrown on Edgartown beach. These were mostly 

 bleached out white and more or less worn. This species has not yet 

 been identified. I have specimens of it from the coast of Virginia. 



A very curious organism, of which the nature is still uncertain, but 

 which was supposed, at the time it was taken, to belong to the sandy 

 Foraminifera, was often extremely abundant in the clear siliceous sand. 

 They were nearly circular, somewhat flattened or biscuit-sha[)ed, and 

 entirely covered by adherent grains of sand, except that there were 

 several dark-colored, hook-like processes projecting from the circumfer- 

 ence. The size was generally less than a fifth of an inch in diameter, 

 and more frequently not more than .12 to .15 of an inch. When dried they 

 became very friable, and the sand fell asunder at a slight touch, 

 so that the}' then appeared like mere lumps of sand, but they retain 

 their firmness when preserved in alcohol. They were often so abundant 

 in the fine sand that when a dredge-full was washed through a moder- 

 ately fine sieve several hundreds or thousands would sometimes remain 

 in the sieve. 



