NA TURE 



[Feb. II, 1875 



whicli form arenaceous tests. The "warm area," on theotherhand, 

 is covered with Ghhigcriim ooze to an unknown depth ; its sur- 

 face stratum being composed of perfect shells hlled with sarcode, 

 whilst its deeper layers are amorphous. Near the junction of the 

 two areas, but still within the thermal limit of the " warm," sand 

 and Globigeriiia ooze are mingled ; this being peculiarly notice- 

 able on the " Ilolicnia ground," which yielded a large proportion 

 of our most noteworthy captures in this locality. Now, if the 

 bottom-deposit is dependent on the life of the surface-stratum, 

 why should there be this complete absence of GioHgc'riiiaooie over 

 the "cold area," the condition of the surface-stratum being every- 

 where the same ? The author can see no other way of accounting 

 for it than by attributing it to the drift of the cold underflow carry- 

 ing away the Gloliigeriiia: that are subsiding through it, towards 

 the deep b.asin of tne Atlantic, into which he believes that under- 

 flow to discharge itself. Prof. Wyville Thomson, however, 

 denies any sensible movement to this underflow, continuing to 

 speak of it as "banked up" by the Gulf Stream,* which here 

 (according to him) has a depth of 700 fathoms ; and this very 

 striking example of want of conformity between the surface- 

 fauna and the bottom-deposit consequently remains to be ac- 

 counted for on his hypothesis. 



The other of Prof. Wyville Thomson's principal conclusions 

 relates to the origin of the " red clay," which he lound covering 

 large are^s in the Atlantic, and met with also between l<.ergue- 

 len's Laud and Melbourne. Into this red clay he describes the 

 Clobigerina ooze as graduating through the "grey ooze;" and 

 he aftirms this transition to be essentially dependent on the 

 depth of the bottom. And from the data which he gives he 

 considers it an indubitable inference "that the red clay is essen- 

 tially the insoluble 1 esidue, the ash, as it were, of the calcareous 

 organisms which foiiu the Globigeriiia ooze after the calcareous 

 matter has been by some means removed," This inference he 

 considers to have been cenfirmed by the analysis of several 

 samples of Globigciina ocze, " always with the result that a 

 small proportion of a red sediment remains, which possesses 

 all the characttis of the red clay." Prof. Wyville Thom- 

 son further suggests that the removal ot the calcareous matter 

 may be due to the presence of an excess of carbonic acid in the 

 bottom waters, and to the derivation of this water in great part 

 from circumpolar freshwater ice, so that, being comparatively 

 free from carbonate of lime, its solvent power for that substance 

 is greater than that of the su[ cijacent waters of the ocean, lie 

 might have added probability to his hypothesis, if he had cited 

 the observations of Mr. .Sorby as to the increase of solvent power 

 for carbonate of lime possessed by water under greatly augmented 

 pressure, t 



The author, however, after a careful examination of the data 

 given by Prof, Wyville Thomson, thinks it is clear that no con- 

 stant relation exists betweeen depth and the nature of the 

 bottom. 



The author agrees with Prof. Wyville Thomson in thinking 

 that the remarkable ' uniformity of the "red clay" deposit, 

 coupled with its peculiar composition, indicates that it is not 

 derived from the land ; and the author's suggestion is based on 

 its near relation in composition, notwithstanding its great differ- 

 ence in appearance, to Glaucoiiile — the mineral of which the 

 greensands that occur in various geological formations are for the 

 most part composed, and which is a silicate of peroxide of iron 

 and alumina. 



It is well known that Prof. Ehrenberg, in 1853,$ drew atten- 

 tion to the fact that the grains ol these green sands are for the 

 most part, if not entirely, iuU-nial casts of P'oraminifera ; the 

 sarcodic bodies of the animals having been replaced by glau- 

 conite, and the calcareous shells subsequently got rid of, either 

 by abrasion, or by some solvent which does not attack their con- 

 tents. It was soon afterwards shown by Prof. Bailey (U.S.), 

 that in certain localities a like replacement is going on at the 

 present time, the chambers of recent Foraminifera being occa- 

 sionally found to be occupied by mineral deposit, which, when 

 the shell has been dissolved away by dilute acid, presents a per- 

 fect internal cast of its cavities. The author then referred in 

 this connection to the researches of Messrs, Parker and Rupert 

 Jones on Mr. Peete Jukes's Australian dredgings, and to his own 

 on a portion of the loraminiferal sand dredged by Capt, Spratt 

 in the ^ligean (kindly placed m his hands by Rlr. J. Gwyn 

 Jeffreys). 



* See his " Depths of the Sea," p. 400. 



+ Proceedings of the Royal Society, 1862-63, P' 538- 



X " Uebcr den Gruusand und seine Krlauterung des organischen Lebens," 

 in Abhaadl, der Konigl, Agad, dcr Wissensch. iw Bttliu, 1855, p. 85. 



The author said that alike in Mr. Jukes's and in Capt. Spratt's 

 dredgings, some of these casts are in green silicates, and some 

 in ochreous, correspond ing precisely to the two kinds of fossil 

 casts described by Prof. Ehrenberg. 



The author, in the residue left after the decalcification of Capt. 

 Spratt's dredgings, noticed a number of small particles ot red 

 clay, some of them presenting no definite shape, whilst others 

 approximated sufficiently closely in form and size to the green • 

 and ochreous "internal casts" to induce him to surmise that 

 these also had been originally deposited in the chambers of Fora- 

 minifera, their material being probably very nearly the same, ^ 

 although its state of aggregation is different. And if this was 

 their real origin, he would be disposed to extend the same view 

 to the red clay of ihe Clialleiiger soundings. 



In conclusion, the author submitted that if the red clay is (as 

 he is disposed to believe) a derivation of the Globigeriiia ooze, 

 its pi eduction is more jirobably due to 3. post-mortem deposit in 

 the chambers of the Foraminifera than to the appropriation of 

 its material by the living animals in the formation of their shells. 

 That deposit may have had the character, in the first instance, of 

 either the green or the ochreous silicate of alumina and iron, 

 which constitutes the material of the internal casts ; and may 

 have been subsequently changed in its character by a metamor- 

 phic action analogous to that which changes felspar into clay. The 

 presence of an excess of carbonic acid would have an important 

 share in such a metamorphosis, and the same agency (cspeciafly 

 when operating under great pressure) would be fully competent 

 to effect the removal of the calcareous shells. This seems to the 

 author the most probable mode of accounting for their disappear- 

 ance from a deep-sea deposit, where no mechanical cause can be 

 invoked. IJut in shallower wa'ers, where the same excess of 

 carbonic acid does not exist, and the aid of pressure is wanting, 

 but where a movement of water over the bottom is produced by 

 tides and currents, he is disposed rather to attribute the dis- 

 appearance of the shells to mechanical abrasion. This is the 

 explanation the author would be disposed to give of the dis- 

 apj.earance of the shells Irom the green sand brought up by the 

 C//(;//iv/;,v/- in the course of the Agulhas Current; but whether 

 it was mechanical abrasion or chemical solution that removed the 

 foiaminiferal shells whose internal casts formed the Greensand 

 deposit of the Cret.iceous epoch, must remain for the present an 

 open question. 



Linneaii Society, Feb. 4.— Dr. G. J. Allman, F.R.S., 

 president, in the chair. — Capt. Gilbert Mair and Dr. Llewellyn 

 Powell were elected Fellows. — The iollowing papers were read : 

 — On Aris^iia speciosum, by Mr. J. Gammie. The remarkable 

 appendage to the spadixof this plant had been supposed to be con- 

 nected with acontrivance to favour cross-fertilisation, but the author 

 h.id been unable to find that it is visited by insects.^On the Algcc 

 of Simon's Pay. —On the Fungi collected during the Cliallengcr 

 Expedition, by the Rev. M. J. Berkeley. — On the plants and 

 insects of Kerguelen's Land, by Mr. H. N. Moseley. The 

 author enumerated the insects met with during the visit of the 

 party, including only one winged gnat, all the rest being apte- 

 rous. A great quantity of one species were seen crawling over 

 the Fringlca, but not on the infloresence.— On the origin and pre- 

 vailing systems of phyllotaxis, by the Rev. G. Henslow. In 

 this elaborate paper the object of the author appeared to be to 

 trace all existing systems of phyllotaxis to modilrcations of the 

 decussate as the simplest. — A discussion followed, in which Mr. 

 Hiein, Prof. Dyer, Mr. A. W. Bennett, and Dr. Masters took 

 part. 



Zoological Society, Feb. 2.— Dr. A. Giinther, F.R.S., vice- 

 president, in the chair. — Mr. Sclater exhibited and made remarks 

 on a fine skin and skull of a female Huemul [Ceiiius ckilensis), 

 and a pair of horns of an adult male of the same animal, for- 

 warded by Mr. Edwjn C. Reed, of the National Museum, San- 

 tiago, Chili. — Dr. E. Hamilton exhibited and made remarks on 

 some deformed sterna of the common fowk — Prof. A. H. Garrod 

 read a paper on the kangaroo called Haliiiaturus luctuosus by 

 D'Albertis, and on its alfinities, in which such points in the 

 anatomy ol the type-specimen were described as served to ex- 

 plain its systematic position. It was shown from the form of the 

 premolar and molar teeth, from the nature of the fur, and from 

 other minor details, that this species must be placed in the same 

 genus as the Dorcopsis bruiiii (Miiller), named more correctly 

 D. muelleri (Schlegel). The species, therefore, should stand as 

 Dorcopsis luctuosa, being the only other known species of the 

 genus. It was also shown ^^iXDorcapsis, together \i'\!^D<ndro- 



