412 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



Polyps. 



Page. 



Metridium marginatum 329 



Sagartia leucoleua 329 



Page. 

 Astrangia Danse 408 



Page. 



Grantia ciliata 330 



Cliona sulphurea 409 



Tedania .- 409 



Sponge, red species 409 



PROTOZOA. 



Sponges. 



Pase. 



Ohalina oculata 409 



Ohalina, slender species 409 



Several other sponges 409 



Foraminifera. 



Page. 

 Numerous species 421 



6. FAUNA OF THE GRAVELLY AND SHELLY BOTTOMS OF THE BAYS 



AND SOUNDS. 



Bottoms composed of gravel or pebbles, often with, small stones, and 

 generally with a considerable proportion of dead and usually broken sliells, 

 were of frequent occurence in Vineyard Sound, and a few such localities 

 were found in Buzzard's Bay. Similar bottoms of small extent have 

 also been examined in Long Island Sound, near New Haven. These 

 bottoms are generally the most productive and agreeable for the 

 dredger, for they are the favorite abodes of large numbers of animals 

 of all classes, and the contents of the dredge are often so clean that 

 they require little if any washing in the sieves. They vary much, 

 however, in character, some of them consisting mostly of gravel, with 

 pebbles and perhaps small scattered boulders ; others consist largely 

 of broken shells, especially those of Mactra solidissima and Crepidula 

 fomicata, mixed with more or less gravel, sand, and mud. Others 

 are so completely overgrown with the various large compound asci- 

 dians described above, that they might well be called "ascidian 

 bottoms." In many jdaces, however, there are patches of mud or sand, 

 scattered here and there over a bottom which is mostly of gravel and 

 shells, so that the dredge will often bring up more or less mud or sand, 

 with some of the animals peculiar to such patches, mixed with those 

 peculiar to the gravelly bottoms, thus augmenting the number and 

 variety of animals. In other cases more or less mud and sand may be 

 mixed with the gravel throughout, or the bottom may be in process of 

 changing from mud or sand to gravel, or the contrary, owing to frequent 

 changes in the directions of the currents, produced chiefly by the action 

 of storms upon the shoals and bars of sand. Hence it is often difficult to 



