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 faunae 

 by isolated mountain chains. 



Hexactinellidse, brachiopods, Pleurotomarise, Spirulse, crinoids, 

 deep-sea corals, Echinothurise, Ananchytidee, Pourtalesise, Bri- 

 singse, Elasoj)odise, Macruroids, Ophidiidse, Willemoesise, 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 lev el 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 ver}^ moderate dej^th ; 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 uj^per 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, moUusks, anne- 



^ Dr. Norman lias given a detailed list Newcastle-on-Tyne, VIII., Part I.) In 

 of the species dredged in the Northern the description of the characteristic deep- 

 Atlantic on bottom covered by red clay, sea animals from the West Indies, the 

 and another of the fauna known to live Gnlf of Mexico, and the east coast of the 

 at greater depths than one thousand fath- United States will be found references to 

 oms. (Presidential Address, Tyneside the principal types of the Atlantic abys- 

 Naturalists' Field Club, May, 1881, Trans, sal fauna. 

 Nat. Hist. Soc. Northumb., Durham, and 



