296 Messrs. Parker and Jones on 



by the same varieties that existed when the Chalk was formed ; 

 and that the Atlantic ooze, in which other Mollusks, Echino- 

 derms, Crustacea, and Vertebrata than those of the Chalk 

 occur, cannot be regarded as " Chalk " in a strictly geological 

 or palffiontological sense. In a lithological (or halibiolitho- 

 gical) sense — that is, with reference to their general origin 

 from calcareous organisms, and regarded as having been all 

 similarly formed in successive, never quite disconnected, but 

 partially continuous oceans — nearly all limestones would come 

 under the geological name of the oldest of the known series ; 

 but, although supported by the known occurrence of persis- 

 tent Foraminiferal types through period after period, such a 

 classification would be vague and useless. 



On this interesting geological subject see also Mr. Prest- 

 wich's Anniversary Address to the Geological Society of 

 London, Feb. 17, 1871 (Quart. Journ. Geol, Soc. No. 106). 

 The number of species and notable varieties of Foraminifera 

 common to the Chalk and the North-Atlantic ooze, as shown 

 by our table in that Address, is now known to be greater, 

 since our correlation of the Chalk specimens figured in the 

 ^ Mikrogeologie ' with other published forms. Both in this 

 instance and in the description of the North-Atlantic Forami- 

 nifera (Phil. Trans. 1865) we had to refrain from reference to 

 Dr. Ehrenberg's ' Mikrogeologie ' and previous memoirs, not 

 having had the opportunity of working over this great store 

 of information, and at the same time having recognized how 

 little the apparent conclusions of the veteran naturalist co- 

 incided with those arrived at by others. Now that our biblio- 

 graphic studies bring us, in chronological order, to the earliest 

 of Dr. Ehrenberg's memoirs, we have willingly entered on 

 the somewhat arduous and responsible labour of comparing 

 and identifying as far as possible all the Foraminifera he has 

 so abundantly provided in his successive publications. 



Species and notable Varieties from the Chalk of Meudouj 

 figured hy Ehrenherg. 



1. Lagena globosa [Montagu). 



2. Nodosaria ovicula, Z)' Orh. 



3. Cristellaria cultrata [Montfort). 



4. Polymorphina Thouini, /)' Orb. 



5. Bolivina punctata, Z)' Orb. 



6. Virgulina squamosa, Z>' Orb. 

 7. tegulata, Reuss. 



8. ■ asparagus [Ehr.). 



9. Schreibersii, Czj'zek. 



10. Textilaria agglutinans, D^Orb. 



