392 Mr. Gwyn Jeffreys on Dredging among the Hebrides. 



doubt can be entertained. I have myself seen a number of 

 Antedon (or Comatula) celticus clinging to the rope several feet 

 from the dredge when it was taken up from about 60 fathoms. 

 These starfishes must have crawled up the rope while the dredge 

 was in motion or being hauled in, because no part of the rope 

 had lain on the ground. Dr. Carpenter tells me that Antedon 

 rosaceus has the same habit of crawling up and clasping a rope 

 in shallow water. 



The greatest depth marked on the Admiralty charts in any 

 part of the Hebridean sea-bed which I examined is 132 fathoms. 

 Here I got several kinds of living Foraminifera. Nineteen 

 years ago I dredged near the same ground, in 116 fathoms, a fine 

 cluster of one of the compound Tunicata, Diazona Hebridica, 

 of a greenish-pink colour. I do not mention this as a great or 

 even considerable depth. Sars* and Korenf have done much 

 more on the coasts of Norway ; their dredging-explorations 

 extended to 800 fathoms. In the paper from which I have 

 extracted the above remarks as to the distribution of animal life 

 in the depths of the sea, Professor Sars has enumerated no less 

 than 52 species and distinct varieties of animals found by him 

 at the depth of 300 fathoms. They may be thus classified : — 

 Porifera (Sponges) 2; Rhizopoda (Foraminifera) 19; Polypi 

 (Actinozoa) 7; Mollusca (Polyzoa 8, Tunicata 1, Mollusca proper 

 10) 19; and Vermes (Annelida) 5. He has also specified several 

 Echinoderms, Cirripeds, and Crustacea, as inhabiting somev/hat 

 less depths, viz. from 200 to 250 fathoms. The observations 

 of the learned Norwegian zoologist confirm those of Sir James 

 Ross and Dr. Wallich, namely : — 



1st. That the temperature of the sea is uniform (39°*5 Fahr.) 

 over the whole globe, below a certain line which forms an isother- 

 mal curve, with but slight oscillations caused by changes of the 

 atmosphere. This curve has its greatest depth at the Equator, 

 but reaches the surface of the ocean in lat. 56° 62', and dips 

 again as it approaches the pole from this point. 



2nd. Although the pressure of the water is enormous at great 

 depths, and in 300 fathoms is equal to about 56 atmospheres 

 or 840 lbs. on the square inch J, yet the most brittle and delicate 

 animals (such as Polyzoa and Polyps) inhabiting such depths do 

 not appear to suffer the slightest injury. Their structure is 

 porous and permeable by liquids, or accessible to an endosmotic 

 influence by which the pressure is easily resisted. 



* Reise i Lofoten og Finmarken, 1849. 



t Nyt Mag. Naturw. 1856, 



X The Norse skaalpund is 10 per cent, more than the English lb. avoir- 

 dupois. Sixteen Norwegian square inches are equal to seventeen English 

 square inches. 



