1869.] 



on the Scientific Exploration of the Deep Sea. 



435 



the region of the "Warm and Cold Areas " traversed last year in the 'Light- 

 ning,' with the special view of determining, if possible, (1) the Physical con- 

 ditions on which depends the remarkable contrast then discovered between 

 their fo^owz-temperatures, the Sea-bed being of nearly the same depth 

 throughout, and their si^/ace-temperatures being alike ; and (2) the in- 

 fluence of this difference upon the distribution of Animal life, and on the 

 nature of the Sea-bed itself. 



CI. As it was requisite that the boilers of the 'Porcupine' should be 

 thoroughly cleansed after her return from the Second Cruise, we did not leave 

 Belfast (to which port she had gone round from Cork) until "Wednesday, 

 August 1 1th ; when we made direct for Stornoway as our final point of depar- 

 ture, arriving there on Friday the 13th. Having taken in as much coal as 

 could be safely stowed on deck, as well as below, we left Stornoway on the 

 afternoon of Sunday the 1 5th, and proceeded in the direction of the spot on 

 which we had made our most successful dredging of last year ('Lightning' 

 Report, § 16), and which we had come to call the Ho! tenia- ground*. 

 Our dredging on this ground (Station 47) again proved remarkably success- 

 ful, bringing up numerous specimens of Holtenia, of Hyalonema (one of 

 them constituting a new species), of Adrasta infundibulum (a type allied 

 to Hyalonema), and of Tisiphonia (a remarkable genus of Siliceous 

 Sponges, obtained, like Holtenia, for the first time last year, of which a 

 description, by Prof. Wyville Thomson, will soon be presented to the 

 Royal Society), besides many other specimens of great interest, some of 

 which appear to be new types. The experience of the 650 fathoms' 

 dredge last year having led us to put aside and preserve the siftinys, instead 

 of attempting to pick them over at the time, we have since found them to 

 yield an extraordinarily rich harvest of Foraminifera, including not 

 merely the types mentioned in the 'Lightning' Report (§ 16), but a great 

 number of others, especially of the Arenaceous Order, in which the shelly 

 covering is replaced by a " test" composed of sand-grains more or less 

 firmly cemented together. Although the Holtenia-gTOuudi lies within the 

 Warm area, the Sea-bed of which is ordinarily covered by Globiyerina- 

 mud ('Lightning' Report, p. 190), yet this mud here contains a consi- 

 derable admixture of sand, obviously derived from the Cold area with 

 which it is here in immediate proximity. For this sand, when separated 

 from the Globiyerina-mud, corresponds precisely in its character with that 

 of the Cold area, being especially distinguished by the admixture of 

 particles of Augite and other minerals having an undoubtedly Volcanic 

 source. This admixture is very perceptible to the experienced eye 

 in the " tests" of Astrorhiza and other Arenaceous Foraminifera abundant 



* The largest of the extraordinary Vitreous Sponges dredged in this locality last 

 year has been described by Prof Wyville Thomson, in a Memoir presented to the 

 Eoyal Society on June 17, and since published in the Philosophical Transactions for 

 1869, under the generic name Holtenia, in compliment to our excellent friend Ampfc- 

 man Holten, the Governor of the Faroe Islands. 



