518 ON THE EXISTENCE AT GREAT SEA-DEPTHS OF 
In the Palzeozoic deposits, on the other hand, only three or four genera 
have been met with, and examples of these are rare. As already 
remarked, our Canadian rocks of this age have not yet offered any 
representatives of the Order. 
9. Holothurida.—This Order comprises various more or less soft- 
bodied marine animals, of which the Holothuria or “‘ sea-cucumber ” 
may be taken as a type. Fossil representatives are of exceedingly 
doubtful occurrence. None belong to Canadian rocks. 
This concludes our rapid sketch of the sub-kingdoms Protozoa 
and RapiarA. The Moxtusca and other types will come under 
review in our next Number. ; 
OBSERVATIONS ON THE EXISTENCE OF VARIOUS 
MOLLUSKS AND ZOOPHYTES AT GREAT 
SEA DEPTHS. 
BY M. MILNE EDWARDS. 
(Translated from the Comptes Rendus of July 15, 1861.) 
A more accurate knowledge of the depths assigned by Nature to 
the various species which inhabit the sea, has been rendered especially 
desirable by the bathymetrical researches of the late Edward Forbes 
and other observers, and also by the relations which appear to obtain 
between the existing and geological distribution of marine animals. 
I have therefore eagerly availed myself of all opportunities which - 
seemed favorable for the prosecution of this class of observations. 
M. Valenciennes has kindly presented me with several shells pos- 
Sessing much interest from the remarkable depths at which they were 
obtained. One of these is the Voluta Junonia (Sch.) found by Capt. 
B. Letourneur in the Gulf of Mexico at a depth of about 130 metres 
[=426% feet]. Another belongs to Lima excavata, dredged by M: 
Hoeg at 487 metres [=1597°8 feet] off the coast of Greenland. This 
latter station much exceeds the lowest zone hitherto assigned to the 
habitations of marine mollusks, but other facts which I am about to 
describe, have proved the existence of these forms, and also of corals; 
at still greater depths. 
waits 
