8 Prof. T. Fuclis on the Deep-sea Fauna. 



seas in shallow water, and in the Arctic seas only in the 



depths** 



Further proofs of the small influence that temperature exerts 

 upon the bathymetrical distribution of organisms are obtained 

 if we examine into the occurrence of the deep-sea fauna at 

 different points. 



In the Arctic Sea, between Norway, Iceland, and the 

 Faroes, we find at the bottom a temperature of from —1° to 

 -2° C. (30°'2 to 28°-4 F.)- Notwithstanding this low tem- 

 perature, the fauna there is extraordinarily rich, and con- 

 sists of the ordinary characteristic deep-sea forms. We find 

 in great abundance deep-sea corals (Lophohelia, Amphihelia, 

 Caryophyllia, Flabellum^ Umbellularia) , Brachiopoda (Tere- 

 bratula septata, Platydia anomioides, &c), vitreous sponges, 

 Echinothurice , Pourtalesice, starfishes, Ophiuraus, Crustacea, 

 and the usual Mollusca of the deep sea. 



Not far removed from this region, to the north-west of 

 Scotland and Ireland, the bottom shows a temperature of 

 ~ to 8°-o C. (43°'7 to 47°-3 F.) in exactly the same depth 

 fore. But although the temperature here is only 8 to 

 j. (14° to 18° F.) higher than in the preceding case, the 

 fauna still shows exactly the same character. Here, again, we 

 find the same genera (Lophohelia, Amphihelia, Caryopliyllia^ 

 Flabellum^ Umbellularia) , and we also find Brachiopoda, 

 vitreous sponges, Echinothurice, Pourtalena^ together with per- 

 fectly similar starfishes, Ophiuraus, Crustaceans, and Mol- 

 lusca ; nay, to a great extent even the species are the same 

 in both regions. 



On the Pour tales Plateau there is a temperature of from 7° to 

 13° C. (44 c '6 to 55°-4 F.) ; and a temperature of at least 13" 

 C, and probably considerably more, must prevail upon the 

 deep-sea bottoms near the island of Barbadoes, upon which, 

 as upon the Pourtales Plateau, the above-mentioned rich deep- 

 sea fauna is found. 



The Mediterranean, as is well known, in the same way as 

 the lied Sea, presents abnormal conditions of temperature, 

 the water from a depth of about 200 fathoms to the bottom 



as befoi 



10° C 



- 



* Semper (< Die natiirliclien Existenzbedingungen der Thiere,' in 

 English under the title of " The Natural Conditions of Existence as they 



affect Animal Life,' 1881) particularly calls attention to this remarkable 

 phenomenon, and endeavours to explain it by the hypothesis that the 

 animate in question requne not so much a definite degree of temperature 

 as a uniform temperature. But a uniform temperature is found in the 

 warm seas at a less depth than in the colder temperate seas. Sars also 

 has quite recently called attention to this phenomenon ( 4 Mollusca xe- 



gionis arcticae Norvegiae ;' Christiania, 1878), 







