112 



THREE CRUISES OF THE " BLAKE.' 



a temperature of over 80° Fahr., which decreases gradually with 

 the depth, till, between 600 and 700 fathoms, it has fallen to 



Fig. 805. — Opliioconis miliaria. |. 



39i°. The American continents on one side, and the Antilles 



Fig. 390. — Opliiomiisium planum. ^-^. 



• on the other, furnish those great land masses the neighborhood 

 of which seems essential to rich and varied marine life. Their 



