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few scattered islands comparable to some parts of the Pacific, 
‘ it formed as truly a portion of the great northern continent as 
it does now/ 
The evidence, which he has to set aside, in favour of the 
Chalk being a truly oceanic deposit, is extremely weighty how- 
ever, and by no means easily disposed of. Its vast extent — 
stretching from Sweden to Bordeaux, and from Ireland to China 
— and its freedom everywhere from impurities derived from the 
degradation of land, are greatly in favour of its oceanic origin. 
The areas that are known to have been denuded, and the enor- 
mous deposits of flint- shingles which characterize the Eocenes 
from their base upward to the most recent gravels, show 
how colossal this denudation has been. 
The Chalk that has escaped seems but the fragment of a 
mass which once passed under the Atlantic, for even the Scilly 
Isles are strewn with flint, and the last remains of it in Devon- 
shire and the north of Ireland are as pure as elsewhere, and 
show no signs whatever in the Chalk itself, towards its western 
boundaries, of the proximity of shores. This vast deposit 
abounds with Globigerina , of species identical with those of the 
modern Atlantic mud, and with coccoliths and discoliths. 
Representative siliceous Sponges are abundant in both, and the 
recent chalk-mud has yielded a large number of the group 
I* or if era vitrea , which find their nearest representatives among 
the Ventriculites of the White Chalk. The Echinoderms of the 
deeper parts of the Atlantic basin are very characteristic, and 
yield an assemblage of forms which represent in a remarkable 
degree the corresponding group in the White Chalk. Species of 
the genus Cidaris are numerous ; some remarkable flexible 
forms of the Diademidae seem to approach the Echinothuria ;* 
Rhizoerinus is closely allied to the chalk Bourgueticrinus, while 
even among fish the genus Beryx, so abundant in the Chalk, has 
been found by Dr. Carpenter, and the fresh light that the pub- 
lication of the deep-sea fish of the Challenger Expedition is likely 
to throw on the subject will be looked forward to with much 
interest. 
Prof. D uncan, t when investigating Corals, became impressed 
with the remarkable persistence of character and absence of 
variability in those of the deep-sea fauna. ‘ The dredging in 
1095 fathoms off the coast of Portugal, which yielded Renta - 
crinus JVyvillc-Thomsoni, Jeffreys, produced many corals; and 
the series presented an eminently Cretaceous facies. The genus 
Bathycyathus, whose species, Sowerbyi } is so well known in the 
Upper Greensand, was represented there by numerous specimens 
of a species closely allied to that form/ 
* Sir Wyville Thomson, Nature , vol. iii. p. 297. 
t Quart. Jour. Geol. Soc. xxvii. p. 437. 
