1456 



CRUSTACEA. 



species, may perhaps show that the waters are less favourable for 

 hardier corals than those of the Feejees, where the range of tempera- 

 ture is from 74° to 80° F. ; but this would be a hasty conclusion, with- 

 out more extended observations. The author was on these islands 

 only for a few hours, and his collections were afterwards lost at the 

 wreck of the Peacock, just as the vessel was terminating the voyage 

 by entering the Columbia River. 



It is unnecessary to remark particularly upon the fitness of the 

 other isocrymals for the purposes of illustrating the geographical dis- 

 tribution of marine species, as this will become apparent from the 

 explanations on the following pages. 



The regions thus bounded require, for convenience of designation, 

 separate names, and the following are therefore proposed. They 

 constitute three larger groups : the first, the Torrid zone or Coral-reef 

 seas, including all below the isocryme of 68° F.; the second, the 

 Temperate zone of the oceans, or the surface between the isocrymes of 

 68° F. and 35° F.; the third, the Frigid zone, or the waters beyond 

 the isocryme of 35° F. 



I. TORRID OR CORAL-REEF ZONE. 



Regions. 



1. Supertorrid, 



2. Torrid, 



3. Subtorrid, 



1. Warm Temperate, 



2. Temperate, 



3. Subtemperate, 



4. Cold Temperate, 



5. Subfrigid, 



II. TEMPERATE ZONE 



Isocrymal limits. 



80° F 



to 80° F 



80° 



to 74° 



74° 



to 68° 



68° 



to 62° 



62° 



to 56° 



56° 



to 50° 



50° 



to 44° 



44° 



to 35° 



1. Frigid, 



III. FRIGID ZONE. 



35° to 26° 



A ninth region — called the Polar — may be added, if it should be 

 found that the distribution of species living in the Frigid zone re- 

 quires it. There are organisms that occur in the ice and snow itself 



