82 GDIDE TO LOCALITIES. 



for several hours at a time. It is usually of a deep flesh color, 

 which in exposed and contracted animals appears much deeper 

 than in expanded ones. Sertularia pumila is another hydroid 

 abundant under and on the rockweed ; and Campanularia flex- 

 itosa, though much rarer in this habitat than in the preceding, 

 also is found. Barnacles are common, and near them occurs 

 Purpura lapillus in considerable numbers and in great variety 

 of form and coloration. The pear-shaped egg-cases of this 

 species may be found usually in clusters attached to the rock or 

 seaweed. They are white or yellow, turning with age to pink or 

 purple. Three species of Littorina always can be found on these 

 rocks. The largest, L. littorea, is extremely abundant and, like 

 all littoral species, shows considerable variation in form and color. 

 The small high-spired species, L. rudis, also is common, and like- 

 wise shows much variation. The spotted variety, L. tenebrosa, also 

 occurs. L. palliata, another common variety, has a low spire and 

 is more globose and smooth. It is sometimes yellow or orange in 

 color ; but more commonly dark brown or olive, not infrequently 

 striped, banded or spotted. 



In the shelter of the ledges is an extensive mussel-bed, and star- 

 fish are not uncommon. They are more abundant however in 

 the immediate vicinity of the ledges, where the large Asterias vul- 

 garis may be seen by the hundred on the muddy bottom and among 

 the eel-grass. A. forbesii also occurs here, but is more common 

 on the ledges. 



The smooth starfish, Oribrella xanguinolenta, sometimes is found 

 on the ledges ; but on the whole it is a rare species on our coast. 

 Clinging to the ledges and to submerged stones and shells, the 

 common limpet, Acme a te.studinaHs, can be found in abundance. 

 It varies somewhat in shape and coloration. On the muddy bottom 

 accessible at the lowest tides, where the water is only from one to 

 two feet in depth, the large hermit crab Eupayurus bernhardus 

 is very abundant. It inhabits the shells of Lunatia heros, Biuxinum 

 iundatum and large shells of Littorina littorea. Upon these shells 

 may be found commonly the polymorphous hydroid Hydractinia 

 polyclina. 



On the eel-grass the curious "no-body-crab," Caprella, may 

 be found ; various species of hydroids as well as gastropods, sim- 

 ilar to those found on the ledges, occur clinging to the eel-grass. 



In the deeper water of the estuary, the large simple hydroid Cory- 



