[337] INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 43 



they pick up the bits of alga* very daintily ; the females use, indifferently 

 either of their small claws for this purpose. They always swallow more, 

 or less sand with their food. Mr. Smith also saw these, crabs engaged 

 in scraping up the surface of the sand where covered with their favorite 

 nlga', which they formed into pellets and carried into their holes, in the 

 same way that they bring sand out, doubtless storing it until needed 

 for food, for he often found large quantities stored in the terminal 

 chamber. Mr. T. M. Prudden has since ascertained that one of the other 

 species of "fiddlers" on our shores (G. minax) is also a vegetarian and 

 feeds upon similar algre, which grow on the muddy salt-marshes. 



The Ocypoda arenaria is a crab allied to the " fiddlers" and similar in 

 some of its habits. It is a southern species, ranging as far as Brazil, 

 and adult specimens have not yet been observed on the coast of New 

 England, but Mr. Smith has observed the young in abundance at Fire 

 Island, and we have the young from Block Island ; it occurs at Great 

 Egg Harbor, New Jersey, of larger size, and therefore it may be looked for 

 on the beaches of Nantucket and Martha's Vineyard. This crab lives on 

 the beaches at, and even far above, high -water mark. It digs large holes 

 like the fiddlers, often in the loose dry sand, back from the shore, yet 

 when disturbed it will sometimes take to the water in order to escape, 

 though it soon returns to the shore. In digging its holes, according to 

 Mr. Smith's observations, it works in the same way as the u fiddler- 

 crabs," except that it is quicker in its motions, and often, instead of car- 

 rying the pellets of sand to a distance from the hole, it throws it away 

 with a sudden and powerful jerk, scattering the sand in every direction, 

 It is even more cautious in its movements, and is always on the alert, even 

 the slightest movement on the part of one who is watching them is 

 sure to send them all into their holes instantly. In color this species 

 imitates the sand very perfectly, especially while young, when they 

 are irregularly mottled and speckled with lighter and darker shades of 

 gray. They also have the habit of crouching down closely upon or 

 into the sand, when suddenly frightened, and aided by their colors will 

 often thus escape observation. At other times they will trust to their 

 speed and scamper over the sand with such swiftness that they are not 

 easily captured. This crab is carnivorous m its habits and, according 

 to Mr. Smith's observations, it lives largely upon the a beach-fleas" 

 (Talorchestia) which inhabit the same localities. It will lie in wait and 

 suddenly spring upon them, very much as a cat catches mice. It also 

 feeds upon dead fishes and other animals that are thrown on the shore 

 by the waves. 



Another inhabitant of the upper part of the sand-beaches, just below 

 high-water mark, is the Scyphacella arenicola SMITH, which has, as yet, 

 been found only on the coast of New Jersey, but probably occurs far- 

 ther north. It is a small, sand-colored Isopod crustacean, which has no 

 near relatives, so far as known, except in New Zealand. It burrows in 

 the sand, making a little conical mound around the mouth of the holes. 

 5 V 



