AMERICAN 
JOURNAL OF SCIENCE AND ARTS. 
[SECOND SERIES.] 
Arr. XVI.—On an Isothermal Oceanic Chart, illustrating the 
over aniecm Distribution of Marine animals ; by James D. 
ANA.* 
Tue temperature of the waters is well known to be one of the 
most influential causes limiting the distribution of marine species 
of life. Before therefore we can make any intelligent comparison 
of the species of different regions, it is necessary to have some 
clear idea of the distribution of temperature in the surface waters 
of the several oceans: and, if we could add also, the results of ob- 
tering observations, but none of a systematic aaa followed 
through each season of the year 
The Map which we present in illustration of this subject 
presents a series of lines of equal surface temperature of the 
oceans. The lines are isocheimal lines, or more sie asocry- 
mal lines ; and where they pass, each exhibits the mean temper- 
ature of the waters along its ae for the coldest thirty consecu- 
tive days of the gee The line for 68° F., for example, passes 
through the ocean where 68° ~ is the mean temperature for 
reme cold weat January i is not pale the e oldest winter 
rt. ee Te aa 
© Bien the A Author's Expl. Exped. Report 
Ssooxo Ssauns, Vol. XVI, No.4i—Septy 1868. oo) 
