32 



Dr. W. Thomson on Holtenia. 



[June 17 j 



are replaceable by chlorine. Pelouze and Cahours* state that the last sub- 

 stitution-product of this hydrocarbon is the compound C G II s Cl 6 . I 

 repeated this experiment, and passed chlorine into pure sextane, first in 

 the diffused and afterwards in the direct sunlight, as long as any action 

 could be observed. Thus I obtained a heavy colourless liquid, which did 

 not distil without decomposition, the analysis of which showed that it had 

 the above composition. 



0*1612 gave 0*4654 silver chloride and 0-00/6 silver. 



Calculated for C 6 H 8 C1 G . Found. 

 72'7 per cent. CI. 72-8 per cent. 



XVII. u On Holtenia, a Genus of Vitreous Sponges." By Wyville 

 Thomson, LL.D., F.R.S., Professor of Natural Science in 

 Queen's College, Belfast. 



(Abstract.) 



During the deep-sea dredging cruise of H.M.S. ' Lightning' in the 

 autumn of the year 1868, the dredge brought up, on the 6th of Septem- 

 ber, from a depth of 530 fathoms, in lat. 59° 36' N., and long. 7° 20' W., 

 about 20 miles beyond the 100-fathom line of the Coast Survey of Scot- 

 land, fine, grey, oozy mud, with forty or fifty entire examples of several 

 species of siliceous sponges. The minimum temperature indicated by 

 several registering thermometers was 47°'3 F., the surface temperature 

 for the several localities being 52 Q, 5 F. 



The mud brought up consisted chiefly of minute amorphous particles 

 of carbonate of lime, with a considerable proportion of living Globigerince 

 and other Foraminifera, and of the "coccoliths" and " coccospheres," 

 so characteristic of the chalk- mud of the warmer area of the Atlantic. 

 The sponges belonged to four genera ; one of these was the genus Hyalo- 

 nema, previously represented by the singular glass-rope sponges of Japan 

 and the coast of Portugal, and the other three genera were new to science. 

 One of these latter was the subject of the paper. 



Associated with the sponges were representatives, usually of a small size, 

 of the Mollusca, the Crustacea and Annelides, the Echinodermata, and the 

 Ccelenterata, with numerous large and remarkable rhizopods. Many of 

 the higher invertebrates were brightly coloured and had eyes. 



Four nearly perfect specimens of the sponge described in the memoir 

 were procured. 



Holtenia, n. g.f 



H. Carpenteri, n. sp. 



The body of the sponge is nearly globular or oval. Normal, and 



* Comptes Rendus, vol. liv. p. 1241. 



t The genus is named in compliment to M. Holten, Governor of the Faroe Islands, 

 and the species is dedicated to Dr. W. B. Carpenter, V.P.R.S., with whom the author 

 was associated in the conduct of the expedition. 



