208 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [502| 
The color is chocolate-brown, with bright red, ligulate, dorsal branchize 
on the anterior third of the body. The two large tentacles exceed in 
length three times the breadth of the body; they are often coiled up, and 
are greenish in color. This worm is three or four inches long. 
A large purple Meckelia (MU. lurida V.) was dredged in two localities. 
Among the Mollusks there are but few species that are characteristic 
of these bottoms, and probably none that are peculiar to them, unless 
some of the Ascidians should prove to be so. The Molgula arenata (p. 
426, Plate XX XIII, fig. 251) is often common even on loose siliceous 
sand and gravel, with which it forms a coating over its body. The 
Molgula producta was dredged in some numbers on a bottom of fine 
sand, with some mud. The integument is thin, translucent, closely 
covered with a layer of fine sand; the tubes are transparent, whitish or 
flesh-color, sometimes pink at the ends; anal tube with four, and branchial 
with six, flake-white, longitudinal stripes, and often with a circle of flake- 
white spots at the base outside, and other spots within. The anal ori-’ 
fice is square, but the branchial is either subcircular or squarish, in 
expansion, and destitute of distinct lobes or papille, in this respect dif- 
fering from all the other species of the genus. The branchial tube is 
generally a little the longest, and both of them are somewhat tapered, 
with a swollen base. 
The Glandula arenicola is another nearly globular Ascidian, which lives, 
like the two preceding, free in the sand, and covers itself with a closely- 
adherent coating of sand. This species grows to be about half an inch 
in diameter, and can easily be distinguished from the last by its much 
smaller tubes, both of which have small square orifices, and by its thicker 
and firmer integument, in which the sand appears to be somewhat im- 
bedded. At the base there are some slender fibers for anchoring it more 
securely in the sand. This was dredged by Mr. Prudden, off Cuttyhunk 
Island, in 1872. Messrs. Smith and Harger dredged it in great abun- 
dance last year on St. Georges Bank, on a bottom of clear siliceous sand, 
in 28 fathoms. Dr. Dawson has also dredged it in Murray Bay, in the 
St. Lawrence River. It is, therefore, a decidedly northern species. 
Another species of Glandula also occurred on the true sandy bottoms. 
The specimens of this were all small, mostly less than a fifth of an inch 
in diameter, and the integument was densely covered by rather coarse 
and very firmly adherent grains of sand, in several layers; the sand 
completely concealed the tubes from view in all the specimens observed, 
and it was not sufficiently studied while living to afford an accurate 
description. 
The Bryozoa and Hydroids that are found on the sandy bottoms are 
mostly attached to dead shells and small stones that are scattered over 
the surface. 
Of Echinoderms several species occur on the hard bottoms of fine, 
compact sand, or sandy mud, but most of these are more at home on 
rocky bottoms. 
