Ixxxvill PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 
greatest density of water in the ocean, is not that which experiments 
in the cabinet would have led us to expect. Dr. Marcet found that 
sea-water decreased in volume until it reached 22°, when it expanded 
a little, and continued to do so down to a temperature of between 
19° and 18°, when it expanded suddenly and became ice with a 
temperature of 28°. According to M. Erman, salt water of the 
specific gravity of 1°027 diminishes in volume down to 25° Fahr., 
not reaching its maximum density until congelation. The tempera- 
ture of the most dense sea-water observed so constantly by Sir James 
Ross, is about that which numerous experiments show as that of the 
greatest density of fresh water. Dr. Hope and Professor Moll found: 
the latter to be between 39°°5 and 40° Fahr., and Professor Hallstrom 
states it to be 39°°394 Fahr. The observations of Sir James Ross 
would show that the temperature of the ocean-waters, which may be 
considered to vary in specific gravity from about 1-027 to 1-028, is 
the same with fresh water, and the mass of evidence he adduces, sup- 
posing no instrumental errors, would prove that the temperature of 
39°°5 is that of the most dense water of the sea, and if not corre- 
sponding with experiments in the cabimet, shows either that there is 
some modifying cause beneath the waters of the ocean, producing a 
higher temperature than should otherwise be, or that there were 
sources of error in the cabinet experiments not observed. 
It did not escape the Commander of this voyage, that the uniform 
temperature of so much of the ocean might be favourable for the 
passage of marine animals from northern to southern regions, if the 
animals were such as to disregard the pressure of water under the 
equator and in the tropics. He observes that arctic marine creatures 
might pass to antarctic regions with only a difference in temperature - 
of 5°, and a pressure of 2000 feet of water in the tropics. 
In the region of Victoria Land we see a striking example of the ex- 
tension of marine life, and of aquatic mammalia and birds dependent 
upon it, beyond terrestrial vegetable life and the animals consuming 
it. To this, no doubt, the equal temperature of the mass of waters 
beneath certain depths gives great aid, and as a whole these tempe- 
ratures are less variable in the sea, and fall less low than in the 
atmosphere, the covering of ice protecting the waters from the in- 
tensity of cold to which they would be otherwise subject. 
Live corals were taken up from the depth of 1620 and 1800 feet 
off Victoria Land, and from the same situations Chitons and other 
molluses, with Serpule adhering to stones and shells, were obtained *. 
Looking at the temperature of the sea obtaimed off Victoria Land by 
Sir James Ross, and the probable changes effected durmg the winter 
months, due allowance being made for an ice-covering, these animals 
would appear exposed to very moderate changes of temperature. 
* These corals were examined by Mr. Charles Stokes, who found them to con- 
sist of three species of Lepralia, Retepora cellulosa, Hornera frondiculata (Lamou- 
roux), Primnoa Rossii, Melitea Australis, and Madrepora fissurata. He remarks 
that Primnoa lepadifera is found in from 150 to 300 fathoms, off the coast of 
Norway, and Prof. Forbes is given as authority for a species of Primnoa in 278 
fathoms off Staten Land. 
