1504 CRUSTACEA. 



tion of individuals of the several species. Crustacean life, of this 

 tribe, is far the most prolific in the warm waters of the globe. Crus- 

 tacea are very abundant about coral islands, far exceeding what may 

 be found in other regions. 



XV. The actual mass of Brachyura appears also to be the largest 

 in the tropics, although there are genera, as Macrocheira and Cancer, 

 which have their largest species in the colder waters, and which 

 exceed in size any other Brachyura. The genera Atergatis, Carpilius, 

 Xantho, Menippe, Zozymus, Eriphia, Thalamita, Charybdis, Calappa, 

 besides others of the Torrid zone, contain many large species, which 

 are of very common occurrence; while the cold-water genera of Maioids 

 appear to be much less prolific in species, and the other genera, 

 though abounding in individuals, as Cancer and Lupa, are still but 

 few in number. Any very exact comparison, however, of the two 

 zones in this particular cannot be made without more data than have 

 yet been collected. 



