123 
1878.J Notices of Books. 
all represented in the fauna of the abyss, occur in peculiar pro- 
portions. Mollusca (shell-fish), brachyurous Crustaceans, and 
Annelida are scarce, whilst Echinodermata and Porifera were 
largely preponderate. Below 500 fathoms the fauna presents 
the same general features in all parts of the world. Deep-sea 
genera are either cosmopolitan in their distribution, or if differ- 
ing in distant localities are to a marked degree mutually repre- 
sentative. It was anticipated that the deep-sea fauna would be 
more closely related than the littoral fauna to the faunae of the 
secondary and tertiary periods. This expectation has been real- 
ised to a certain extent, though the number of types discovered 
which had been supposed extindt is not large. The most cha- 
racteristic deep-sea forms, including those most closely related 
to extinCt types were found in the greatest abundance and in the 
largest size in the Southern ocean, and the “ general character 
of the faunae of the Atlantic and of the Pacific gives the impres- 
sion that the migration of species has taken place in a northerly 
direction.” This capital observation, we must remark, confirms 
the converse conclusion formed as to the distribution of land- 
animals, which are supposed to have spread from the northern 
hemisphere southwards. In other words, terrestrial forms have 
originated in and have been distributed from the greatest mass 
of land, just as marine forms have originated in and have spread 
out from the greatest mass of water. The deep-sea fauna gene- 
rally, as might be expedited, resembles the littoral fauna of high 
latitudes, the physical conditions to which it is exposed being 
nearly identical. A new order of animals approaching to but 
still distinCl from the Radiolarians has been discovered and has 
received the name “ Challengerida.” 
No less important are the physical and hydrographical results. 
We find indeed, in the present volumes, no observations throwing 
•any light on former westward extensions of the eastern continent 
or eastward prolongations of America. The question whether 
Atlantis was a large island south-westward of the Canaries, or a 
large and level trad reaching to the east of the Lesser Antilles, 
according to Mr. Belt’s suggestion, remains precisely where it 
was. It is indeed remarked that the Agores form the culmina- 
ting points of a plateau of considerable extent, and that the 
Bermudas present the appearance of an “ atol.” But it may 
now be considered as definitely established that the bed of the 
Atlantic is divided by an axial ridge, and its branches into three 
basins — the eastern, extending from the West of Ireland south- 
wards nearly to the Cape of Good Hope, with an average median 
depth of 2500 fathoms ; the north-western, occupying the great 
eastern bight of the American continent, and having the average 
depth of 3000 fathoms ; and a third opening southwards and 
running along the coast of South America to Cape Orange, and 
having also an average depth of 3000 fathoms. The Atlantic, 
and even the North Pacific, may be, in fadt, regarded as mere 
gulfs or prolongations of the great preponderating water-mass of 
