ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
501 
of the already known species which were captured by the c Caudan ’ have 
not yet been reported from the Bay of Biscay. Amongst these some 
were known from the eastern coasts of America and western coasts of 
Africa, while others had been met with in the Indian or Pacific Oceans ; 
some had been considered as peculiar to the Mediterranean ; of course 
there were among them species which in the Arctic Seas live at lesser 
depths. 
The Mollusca and Brachiopoda are reported on by M. A. Locard 
and by Prof. E. Joubin, the latter naturalist limiting himself to the 
Cephalopoda. Those who are acquainted with the work of M. Locard 
will not be astonished to hear that he has found a number of new species 
and varieties. 
The last part of the present volume is occupied by a short report on 
the Bryozoa by M. L. Calvet. Only one new species appears to have 
been found among the thirty-nine forms on which the author reports. 
This new species is called Smittia Koehleri. 
General Conditions of Existence, and Distribution of Marine 
Organisms.* — Dr. John Murray gave a most interesting discourse on 
this subject to the zoologists who assembled last September at Leyden. 
After pointing out the general chemical and physical characters of sea- 
water, and the nature of submarine deposits, he said that the abundant 
secretion of carbonate of lime in the warm waters of the tropics is partly 
due to chemical, rather than physiological conditions. When neutral 
ammonium carbonate is added to sea-water at a high temperature — 80° 
to 85° F. — the lime salts other than carbonate present in sea-water are 
quickly decomposed, and an immediate precipitate of carbonate of lime 
having properties of arragonite is formed, while if the same experiment 
be carried out at a low temperature — 40° to 45° F. — the carbonate of 
lime separates out very slowly, and, in doing so, takes the form of calcite. 
The recent deep-sea researches have shown that not only is life uni- 
versally present in great abundance at the surface of the sea, and 
probably also, though much more sparsely, in all the intermediate 
depths of the ocean, but also that fishes and all the invertebrate groups 
are spread all over the floor of the ocean in great numbers. The number 
of species per station decreases gradually from 62*8 species per station 
in the shallowest zones to 9 • 4 species per station in the deepest zone. 
On the whole, the deep-sea fauna resembles that of the shallow waters of 
the polar regions much more than that of the shallow waters of the 
tropical regions, in so far that the animals of the deep sea have a re- 
latively small quantity of carbonate of lime in their shells and skeletons ; 
the proportion of genera to species is higher than in the tropics, and 
there is an absence of pelagic or free-swimming larvae. The majority 
of deep-sea species probably live by eating the surface layers of the mud, 
clay, or ooze at the bottom, and by catching or picking up the small 
organisms or minute particles of organic matter which fall from the 
surface, or are washed away from the shallower parts of the ocean. 
These mud-eating species are in turn the prey of numerous rapacious 
animals, armed w r ith peculiar tactile, prehensile, and alluring organs, for 
phosphorescent light plays an important part in the deep sea, and is 
* Report of the 3rd International Congress of Zoology, 1896, pp. 99-111. 
