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going on over some part or other of the North Atlantic sea-bed, 
from the Cretaceous epoch to the present time (as there is much 
reason to think that it did elsewhere in anterior geological 
periods), this mud being not merely a chalk formation, but a 
continuation of the chalk formation ; so that we may he said to 
he still living in the cretaceous epochJ’^ * 
With the earlier part of the preceding paragraph I partly 
agree, but from its concluding sentence I must dissent. Chalk 
chiefly consists of an accumulation of Grlobigerina cretacea, 
associated in cdmost equal proportions with a minute Textil- 
laria and with Coccoliths. The fossil Grlobigerina is probably 
but a mere variety of the recent Gr. bulloides ; hence, so far as it 
is concerned, ancient and modern deposits may have been con- 
tinuous. But in none of the modern Grlobigerina beds which I 
have examined have I found anything resembling the fossil Cre- 
taceous Textillaria, the disappearance of which requires to be 
accounted for. What I believe to be the same species occurs 
abundantly, amongst other modern types of Foraminifera, in the 
recent sandy deposit underlying Boston in Lincolnshire, but 
1 never succeeded in discovering it living in the sea. From some 
unknown cause it has disappeared. On the other hand, our modern 
deposits abound in Diatoms and Eadiolarige, of which no trace 
appears in the true Cretaceous beds. That in the depth of the 
Atlantic Cretaceous and modern deposits may be conformably 
and continuously superimposed is not impossible, but con- 
formable continuity of series does not constitute identity of age 
or of formation. In the Speeton clay of the Yorkshire coast we 
have, in the same blue deposit, a transition from the Oolites to 
the Cretaceous beds. The deposits have continued to accumu- 
late without physical change from the one age to the other, but 
the fomiations to which the upper and lower portions of this clay 
Ijelong are distinct, and represent distinct epochs. Dr. Carpenter 
is disposed to conclude that the higher forms of the Atlantic and 
Cretaceous fauna) will prove to be nearly identical ; but I doubt 
this, and we must not repeat the blunder of Ehrenberg, in the 
case of the tertiary beds of the IMediterranean coasts, which he 
regarded as Cretaceous, because he found that they abounded in 
Cretaceous types of Foraminifera, overlooking the wide ditfer- 
ences presented by the higher organisations of the two forma- 
tions. So in tlie instance under consideration. Owing to the 
low vitality of the Protozoa, some of them have survived the 
clianges which time has wrought in the higher groups of 
animals. The recent Globigerinm and Bathybia are probably 
descendants from tliose which lived during the Cretaceous 
period, Imt tlieir companions are not the same. The abundant 
Textillaria* are replaced by Diatoms and Badiolaria). Instead of 
• Proceedings of the Royal Society,” vol. xvii. p. 192, 
