122 ' PEOCEEDINGS OF THE GEOLOGICAL SOCIETT. [Jan. 24, 



Upper Chalk of Western Europe, the Tertiary beds, and at the present 

 day in the Atlantic ; but it has not been found in the Lower Creta- 

 ceous rocks of Europe, though representatives of it (P. Karsteni, &c.) 

 are not wanting in some of the Secondary formations. P. elegans, 

 another old (Secondary) form, reached a high stage of groAvth and 

 abundance in the sea that deposited the Gault of England and Europe, 

 and has continued since. 



Discorbina has presented no fossil form older than the Tipper Chalk 

 (Maestricht). Since the Cretaceous period it has abounded profusely 

 in the Paris Tertiaries, and in many other localities since ; and it 

 still flourishes. 



Botalia is found in the Gault ; but it seems to have flourished 

 more abundantly in seas of later periods, and is prolific now in the 

 Atlantic and elsewhere. 



Of the other Rotalince, we have not sufficient data for correct 

 observation in the line of research we have here pursued ; except 

 that we may note the isolated occurrence of Gymhrdopora at Maes- 

 tricht, and its apparent absence until the Miocene period, the absence 

 of Calcarina and of Orbitoides before the Chalk, and, on the other 

 hand, the persistence of Tinojjorus and PatelUna through the Cre- 

 taceous and Tertiary to the present age. 



With the RoTALiN^, as with Olobiyerina (of which we intend to 

 treat before long), the chief distinction between the Cretaceous and 

 existing groups is in the progressively increased number of modifi- 

 cations, and among them the incoming of important variations, though 

 few of them are of generic, or even specific, value, — a distinction strong 

 enough, when supported by other known geological and palaeonto- 

 logical considerations, to mark the impropriety of calling the Atlantic 

 ooze " Chalk," except in the sense of a calcareous rock of marine 

 organic origin. That its geological status should not be spoken of in 

 this vague halobiolithological * sense, the painstaking and thoughtful 

 Ehrenberg long ago warned us. He says : — " In consequence of the 

 mass-building Infusoria and Polythalamia [Diatoms, Polycystines, 

 and Eoraminifers], the Secondary formations can now no longer be 

 distinguished from the Tertiary ; and, in accordance with what has 

 been above stated, masses of rock might be formed even at the present 

 time in the ocean, and be raised by volcanic power above the surface, 

 the great mass of which wou.ld, as to its constituents, perfectly 

 resemble the Chalk. Thus, then, the ChaJTc remains still to be dis- 

 tinguished OS a geological formation, but no longer as a species of rocTc 

 by its organic contents.'' ' Taylor's Scientific Memoirs,' vol. iii. 1843, 

 p. 367, § 10 ; ' Edinb. New Phil. Journ.' vol. sxxiv. 1843, p. 260 ; 

 Abhandl. Perl. Akad. fiir 1839, p. 164, 4to, 1841. 



To render our synoptical study of the Eotaliis^je more complete, we 

 propose to compare the oldest forms on some future occasion ; and, 

 for the present, we offer, in a Supplement to this paper, a critical 

 examination and revised nomenclatm'C of such Tertiaiy lioTALiNiE 

 as have been figured and described by Reuss, Bornemann, Karrer, 

 and other palaeontologists, and are not included in the foregoing lists. 



* " Halobiolith " (Ehrenberg) is a stratum of marine organic origin. 



