136 New York State Museum 



rocks affords shelter for a great variety of animals. The 

 animals most characteristic of this zone are the Limpet 

 (Acmaea), the Common Starfish, Jonah Crab, Brown 

 Sea Anemone, Moss Animals (Bryozoa) and the Com- 

 mon Edible Mussel, Periwinkle and Acorn Barnacle 

 which are as abundant as elsewhere. Other forms more 

 or less common at low tide are hydroids, a sponge, the 

 Rock Snail, Seaweed Snail, small crustaceans and the 

 Rock Crab and Green Crab. The pools in this zone add 

 other residents such as Chitons, the Green Sea Urchin, 

 the Horse Mussel or Bearded Mussel (Modiola modiola), 

 nudibranchs or Sea Slugs etc. 



The discussion above will serve to give an under- 

 standing of the character of some of the associations 

 found on a rock beach along our shores, in this case 

 quite typical of New England and the Massachusetts 

 coast in particular. There is perhaps also needed, as 

 in the case of the tide pool fauna, a general survey of 

 the most common forms of the various groups to be 

 searched for on rocks and rocky bottoms. The Finger 

 Sponge (Chalina oculata) is dull red or yellow in 

 color and grows on rocks or shells forming finger- 

 shaped masses about six inches high. It is common 

 north of Cape Cod at depths greater than fifteen feet. 

 The Boring Sponge (Cliona sulphured) is common 

 along the shores from Cape Cod to South Carolina and 

 is abundant in Long Island sound. It is bright sulphur 

 yellow in color and grows in irregular masses of con- 

 siderable size and fine texture. It lives on shells, com- 

 pletely honeycombing them. It is very destructive to 

 the shells of oysters, clams etc. There are many lit- 

 toral forms of hydroids living in the chinks and cran- 

 nies of the rocks and on seaweeds. The sertularians 



