he says, " The whole forms such an assemblage of sedimentary deposits as would probably be presented to observation if a mass of the bed of the Atlantic, 2000 ft. in thickness, were elevated above the waters, and became dry land ; the only essential difference would be in the generic and specific characters of the imbedded animal and vegetable remains." "Whether viewed by naturalists or by geologists, the similarity of origin seems to have occurred to both; and I am not aware that the question of depth ever seriously interfered with this view amongst geologists, who, on the contrary, rather considered the mass and fossils of the chalk to be an indication of the possibility of life at great depths. Both deposits were also found to contain numerous peculiar and simple organisms, which were named Coccoliths* and Coccospheres (noticed by Wallich, Huxley†, and Sorby), while the profusion of the particular Foraminifer the Globigerina, and the later discovery of siliceous Sponges, are other features in common. Except by Mr. Bailey, the presence of Diatoms has not been noticed‡.
Prof. Rupert Jones has kindly filled up for me the following Tables, the results being based chiefly on Messrs. Parker and Jones's excellent account of the Foraminifera from the North Atlantic and Arctic oceans §. They determined 110 species as now living in those seas; and of these they recognized 19 as fossil in the Chalk.
- Mr. Carter now considers this to be a calcareous unicellular alga, the frustules of which form the Coccospheres. He proposes for it the name of Melobesia
unicellularis. It occurs in abundance in the Laminarian zone off the Devonshire coast. Another species, the M. discus, he considers peculiar to the deep Atlantic. Ann. & Mag. Nat. Hist, for March 1871.
† Prof. Huxley states that Dr. Giimbel of Vienna has now discovered these bodies in all sedimentary strata.
‡ Count Ab. Castracane, of Rome, however, has since examined some of the mud obtained in the first ' Porcupine ' expedition at a depth of 14,610 feet, for Diatoms, and reports that he discovered a rare species of Asteromphalos, which he found, for the first time in Europe, in the Adriatic in 1863. He states also that " Specimens of Hemidiscus occur in greater number, and perhaps also some allied species like Euodia, of which I am not aware that, up to the present time, any examples have before been found in Europe ; at least I have not discovered any mention of them in the various authors I possess on the subject. Besides these, the species of Diatoms most abundant in this deposit are the Coscinodisci ; and of these the Coscinodiscus lineatus, Ehr., is the most frequently met with. There are numerous Melosiroe, Bacteriastra, Triceratia, Bacillarioe, Pleurosigmata, Synedroe, Naviculoe," &c. Count Castracane is unable to determine whether these lived at the bottom of the ocean or near the surface. (Accademia Pontificia de' Nuovi Lincei, sess. del 3 Aprile 1870.)
§ Transactions of the Royal Society for 1865.
