660 WHAT IS BATHYBIUS ? 
so that we may be said to be still living in the cretaceous 
epoch. 
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 Globigerina 
cretacea, associated in almost equal proportions with a minute 
Textillaria and with Coccoliths. The fossil Globigerina is 
probably but a mere variety of the recent G. bulloides; 
hence so far as it is concerned, ancient and modern deposits 
may have been continuous. But in none of the modern 
Globigerina beds which I have examined have I found any- 
thing resembiing the fossil Cretaceous Textillaria, the disap- 
pearance 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 I never suc- 
ceeded in discovering it living in the sea. From some un- 
known cause it has disappeared. On the other hand, our 
modern deposits abound in Diatoms and Radiolarie, of 
which no trace appears in the true Cretaceous beds. That 
in the depth of the Atlantic Cretaceous and modern depos- 
its may be conformably and continuously superimposed is 
not impossible, but conformable continuity of series does 
not constitute identity of age or of formation. In the Spee- 
ton 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 accumulate without physical 
change from the one age to the other, but the formations to 
which the upper and lower portions of this clay belong are 
distinct, and represent distinct epochs. Dr. Carpenter is 
disposed to conclude that the higher forms of the Atlantic 
and Cretaceous faune will prove to be nearly identical; but 
I doubt this, and we must not repeat the blunder of Ehren- 
berg, in the case of the tertiary beds of the Mediterranean 






TE = cct which he regarded as Cretaceous, because he found 


*“ Proceedings of the Royal Society," Vol. xvii, p. 192. 

