NOTES ON THE CRABS 



FOUND IN 



NARRAGANSETT BAY. 



WALTER E. SULLIVAN, A. M. 



The crabs have long been objects of observations, but much 

 relating to their life history is yet unknown. This paper is intro- 

 ductory to a study of some of the common crabs of Rhode Island. 

 Such a study seems warranted not only because of the scientific 

 interest involved, but also on account of their increasing commercial 

 value. In this paper a list of the crabs found in these waters is 

 given with enough description for identification, some facts regarding 

 their economic value, and a review of the papers relating to the 

 development of several species from the time of hatching until they 

 have reached the young crab stage. 



In making a list of the crabs I have grouped and described them 

 in a form which I have found convenient for identification. A 

 description by groups rather than by species is employed, because it 

 seems much simpler first to observe to which tribe a particular species 

 belongs and then separate it from the five or six species belonging to 

 that tribe, rather than to separate it from a large number of species 

 described individually. In this method less detail is necessary. 

 The descriptions are based largely on "Synopses of North American 

 Invertebrates," by M. J. Rathbun. Other works used for occasional 

 reference are given in the bibliogi'aphy. 



With a study of some of the common forms in view, the following 

 questions were drawn up for the adults: 1. What is the normal 



