THE DEEP-SEA FAUNA. 163 
meet something analogous to an alpine or arctic fauna and flora 
spreading over wide oceanic areas below the continental regions, 
without the breaks of continuity caused in similar land faunæ 
by isolated mountain chains. 
Hexactinellidx, brachiopods, Pleurotomarie, Spirulæ, erinoids, 
deep-sea corals, Echinothurim, Ananchytide, Pourtalesim, Bri- 
singe, Elasopodie, Macruroids, Ophidiide, Willemoesim, etc., 
are among the most characteristic deep-sea types.' 
There is a gradual transition and disappearance of deep-sea 
types in the continental and littoral zones, just as vegetation 
at the level of the sea passes to that of mountains, and finally 
dies out at varying heights at the snow line. 
An attempt has been made by Fuchs to prove that the dis- 
tribution into littoral, continental, and abyssal zones is not a 
natural one, and that there are but two zones, the littoral and 
abyssal, the limits of which are well defined, being determined 
by the depth to which light penetrates. He bases his conclu- 
sions on the facts that marine vegetation, which is impossible 
without light, and on which so large a number of marine animals 
depend, is limited to a shallow depth ; that the coral reefs and 
banks of mollusca on which another set of animals depend for 
shelter are also confined to a very moderate depth; and, lastly, 
that in the tropics the upper limit of the deep-sea fauna is found 
in depths of ninety to one hundred fathoms. While I do not 
deny that many ancient types to which attention has not yet 
been called do occur in shallow depths, and that the upper limit 
of many of the deep-sea genera extends into the littoral region 
across the continental zone, yet from my own experiences in 
dredging at Barbados, along the slope of the Florida Bank, and 
in the Gulf of Mexico, I may state that a more abundant fauna 
of sponges, gorgonians, echinoderms, crustacea, mollusks, anne- 
1 Dr. Norman has given a detailed list 
of the species dredged in the Northern 
Atlantie on bottom covered by red clay, 
and another of the fauna known to live 
at greater depths than one thousand fath- 
oms. (Presidential Address, Tyneside 
Naturalists’ Field Club, May, 1881, Trans. 
Nat. Hist. Soc. Northumb., Durham, and 
Neweastle-on-Tyne, VIIL, Part I) In 
the description of the characteristic deep- 
sea animals from the West Indies, the 
Gulf of Mexico, and the east coast of the 
United States will be found refercnees to 
the prineipal types of the Atlantie abys- 
sal fauna. 
