136 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [430] 
Polyps. 
bs Page. 
Paractis rapiformis ....-.....2-.26 0 cece ee ee ee ee eee eee ee 363 
PROTOZOA. 
Sponges. 
Page. Page. 
Cliona sulphurea.......... 427 | Massive siliceoussponge.... 427 
Foraminifera. 
Page 
DOVETal SpecleS 34a oes aul See Ge eens Sod ee eeY 421 
II. 8—FAUNA OF THE MUDDY BOTTOMS OF THE BAYS AND SOUNDS. 
The muddy bottoms are inhabited by a considerable number of 
species, which find their true homes in such localities. Most of these 
are either burrowing or tube-dwelling kinds. A few creep or swim 
about over the surface or conceal themselves in the superticial layer of 
mud and vegetable débris. 
The character of the mud itself is quite various, and the different 
kinds are often inhabited by different groups of animals. The mud may 
be very thick, heavy, and tenacious, consisting chiefly of clay; such 
mud is usually inhabited by few species of animals. It may consist of 
finely comminuted sand, mixed with more or less clay; such bottoms are 
more favorable to animal life. In other places it consists partly of one 
of the preceding kinds intimately mixed with large quantities of decay- 
ing vegetable débris, derived chiefly from eel-grass and algze; such mud, 
unless too fetid, is often full of animal life. In some cases, especially 
in well-sheltered localities, where the water is tolerably pure, the mud 
may contain large quantities of living and.dead microscopic organisms, 
both animal and vegetable, and these may even constitute more than 
one-half of the bulk of the mud, which, in such cases, is peculiarly soft 
and flocculent; such mud is extremely favorable to many kinds of ani- 
mals that feed on the microscopic organisms, especially the bivalve 
shells, Holothurians, and many Annelids, and the “ menhaden” among 
fishes. The last variety of bottom, when it has a substratum of sand 
or gravel a few inches below the surface, is the most favorable kind for 
oysters, which grow very rapidly and become very fat in such places. 
In Vineyard Sound and Nantucket Sound muddy bottoms are not 
common, and are mostly of small extent, situated in coves, harbors, or 
in places where the tides form eddies around projecting points of land, 
or in the lee of shoals. 
In Buzzard’s Bay the bottom is muddy over the greater part of its 
area, except a region of sandy and shelly bottom in the central part. 
In Long Island Sound the bottom is generally muddy throughout its 
