HIGHER CRUSTACEA OF NEW YORK CITY 137 



The first pair of thoracic legs are large and chelate, the right being 

 generally larger than the left. The next two pairs are also large and 

 end in simple points, and the last two pairs are much reduced. The 

 abdominal appendages are more or less atrophied, except the last, 

 which are modified into hooks for holding on to the columella of the 

 shell. In the male these are the only pair present, but in the female 

 the others are slightly developed, and to them the eggs are attached 

 as in the other Macrura. 



As the animal increases in size, it takes a larger shell, sometimes 

 killing and eating the original inhabitant and sometimes taking a 

 dead shell which suits it. Considerable has been written on the 

 habits of these forms, and interesting accounts may be found in the 

 works of Verrill and Kingsley cited above. These forms are easily 

 kept in an aquarium. 



Of the two species E . longicarpus is much the commoner 

 and may be found on the sandy bottoms of the bays everywhere. It 

 is the smaller form and usually occupies the shells of Ilyanassa or 

 Anachis, though any small shell may be used. It may be distin- 

 guished by its size and by its elongated and smooth chelae. 



In E . p o 1 1 i c a r i s , on the other hand, the chelae are shorter, 

 stouter and covered with tubercles, and together they form an 

 operculum to close the opening of the shell. This species occupies 

 the shells of Natica and Sycotypus, and is found occasionally under 

 rocks at low water, but usually occurs in deeper water on rocky or 

 shelly bottoms. 



E . longicarpus is frequently found covered with a variety 

 of Hydroid, H y d r a c t i n i a p o 1 y c 1 i n a Agas. a case of com- 

 mensalism. 



Suborder b BRACH VZLJRA 



Decapoda in which the body is proportionally very broad, fre- 

 quently broader than long, and in which the abdomen is much 

 reduced and permanently flexed in a groove on the underside of 

 the cephalothorax. The antennae are short, and the third maxilli- 

 peds are flattened and platelike, forming a covering for the other 

 mouth parts. The first pair of legs are larger than the others and 

 are modified into chelae. The other four pairs terminate in points 



