10 
be due, as suggested by Professor Thomson and his colleagues, to 
the insoluble residue of the calcareous organisms of the Globigerina 
ooze, or to the suggestion of Dr. Carpenter,* that the red clay is the 
result of the decomposition of previously-formed green sand.+ 
Nor are the Foraminifera the only organisms which ally 
the Atlantic deposit to the old chalk sea; for a species of coral, the 
Caryophyllia cylindracea, some genera of Echinoida, as Salenia, 
Cidaris, Pourtalesia ; {| also Mollusca, Crustacea, and the Crinoids, 
Rhizocrinus and Pentacrinus, and Beryx, a ctenoid fish, first com- 
mencing in the chalk, are either allied to or representative of the 
creatures of the chalk sea, which has led some naturalists to infer that 
we are still living in the cretaceous period; but other forms so 
characteristic of this period have long passed away—the numerous 
carnivorous cephalopods, with the exception of the nautilus ; curious 
forms of predaceous fish related to the sharks and others, were the 
scavengers of the ocean, feeding on the numerous invertebrata and on 
the Teleostean fishes, which here first appeared as the Beryx 
and Osmeroides. § 
* Proc. Royal Soc., vol. xxiii., p, 242.—M. Neumayr, Naturforscher, June, 1875. 
+ Prof. A. Church, F.C.S., of the Agricultural College, Cirencester, has examined 
the red chalk, and kindly furnished me with the following remarks :—An ordinary pale 
specimen of red chalk from Hunstanton contained, besides small rounded pebbles and 
grains of quartz of a dark coloured silicate, a yuantity of fine red slime or mud. This 
substance, which constituted over 9 per cent. of the original rock, was separated in the 
following manner: The crushed fragments of red chalk were covered with weak 
Hydrochloric acid, until no lime was thereby removed. By careful washing, the residual 
fine ved matter was separated from the acid solution on the one hand and from the 
silicious grains on the other. After thorough washing and drying, it was submitted to 
analysis, with the following results :— 
In 190 parts. 
62° 
Ralcai). cePeetaes «+ JeeMe s homes lce 
Alumina and ferric oxide ...... 33°4 
MERPTEBID arcs) ceeitisisie tans > 31 
Undetermined 5. i iiaess easels : 15 
Lime and Manganese were absent. 100°0 
The specimens of red chalk on which the above experiments were made were much paler 
in colour than the darker homogeneous specimens analysed by Prof. Church in the 
year 1863. 
5 Mr. W. H. Hudleston, F.G.S., who has paid some attention to the subject, has 
suggested to me that the Iron in the Glauconite found in Cretaceous rocks is peroxidised 
to a very considerable extent, in spite of the green colour usually accompanying the 
protosalts of iron, therefore no additional oxidation is necessary on the supposition that 
the oxide of iron in the Red Chalk is the result of decomposed glauconite. 
Mr. R. C. Clapham says—‘‘It is an interesting question to consider what is the 
cause of the colour in Red Chalk. Prof. Phillips thinks that it is derived from 
decomposed glauconite or decomposed augite (both of which contain peroxide of iron 
and magnesia). It may also be caused by decomposed iron pyrites, as it will be observed 
the analysis shews a trace of sulphate of lime.”—The Geologist, 1863, p. 29. 
See also Prof. Church, ‘On Red Chalk and Red Clay,” Chemical News, May, 1875. 
t We cannot fail to be struck with the persistence of many of the types of the 
chalk up to the present time. This was of course known from the time Lyell first called 
attention to the similarity of the fossils of the Tertiary deposits with the present fauna ; 
it has recently been brought up still more forcibly after several most marked Cretaceous 
genera, Salenia, Hemipedina, Phormosoma, and Pourtalesia were dredged from great 
depths in the West Indies, showing a much more intimate generic connection between 
the present and the chalk than had been admitted.—A. Agassiz, “Illustrated Catalogue 
vf the Museum of Comparative Zoology,” 1874, p. 752. 
§ The curious genus Echinothuria, described by the late Dr. 8. P. Woodward, and 
procured by the late Mr. W. Flower from the Chalk of Kent, is closely related to 
Calveria and Phormosoma ; in all essential family characters they agree. Rhizocrinus 
belongs, with the Chalk genus Bourgueticrinus, to the Apiocrinid, which attained their 
maximum during the Jurassic period, when they were represented by species of the 
genera Apiocrinus and Millericrinus.—‘‘ The Depths of the Sea,” pp. 164, 447. 
