Nomenclature of the Foraminifera. 293 



tains many Foraminifers that abounded afterwards in the Tertiary 

 seas). Whilst both of these Monothalams are extremely abun- 

 dant in the existing seas, in almost every latitude and at every 

 depth, a recent Ovulite has not yet been met with. The very 

 restricted distribution of this species in geological time is 

 remarkable; scarcely another Foraminifer presents us with a 

 similarly brief history, an undescribed form allied to Dactylo- 

 pora affording almost the only parallel (namely, Acicularia Pa- 

 vantina, d'Arch.). 



The cylindrical variety of 0. Margaritula is roughly figured 

 in the 'Tabl. Encycl. Meth.' pi. 479. fig. 8; and the drumstick 

 variety is better figured by Blainville in the ' Diet. Sc. Nat/ 

 Zooph. pi. 48. fig. 3. The large oval Ovulite also is better 

 figured by Blainville (loc. cit. fig. 2) than by Lamarck. Michelin 

 (Icon. Zooph. pi. 46. f. 243) figures a double or twin Ovulite. 

 For references to other figures and notices, see Bronn's ' Leth. 

 Geogn/ 3rd edit. iii. p. 258. 



6. " Discorbis" was instituted by Lamarck (Ann. Mus. vol. v. 

 p. 182) as a generic name for a group of Rotalian Foraminifera. 

 As he had only met with it in the fossil state, he used the term 

 " Discorbites in describing the only fossil form of Discorbis 

 that he knew, according to his customary plan of modifying the 

 generic name of fossil forms. Discorbis and Discorbites are not 

 required as generic terms. 



Discorbites vesicularis. Ann. Mus. v. p. 183 ; viii. pi. 62. f. 7 : 

 Tabl. Enc. Meth. pi. 466. f. 7 a, b, c : Hist. Anim. s. Vert. vii. 

 p. 623. " Fossil ; Grignon." [Defrance, Diet. Sc. Nat. xiii. 

 p. 347, gives us other localities, near Versailles, near Mantes, 

 and near Hauteville : he also adds the description of another 

 species from Piedmont, D. pedemontanus, Def., and mentions 

 the occurrence of what he believes to be three recent species of 

 Discorbis , one from New Holland, one from the Red Sea, and 

 one from Cherbourg.] 



We have in Lamarck's figures some indifferent sketches of a 

 Rotalia (both dextral and sinistral), which seems to us to be one 

 which we most commonly meet with in the Calcaire grossier, 

 a loose-celled and somewhat outspread variety of the more com- 

 pact Rotalia Turbo, d'Orb. (Ann. Sc. Nat. vii. p. 274. No. 39; 

 Modeles, No. 73), which we select as the typical form from 

 amongst a very large group of varieties. The name Discorbites 

 vesicularis is given by Defrance to the specimens figured in the 

 ' Diet. Sc. Nat/ Zool. pi. 14. fig. 2 a, b, c, which are admirable 

 drawings of the variety under notice when in a rather flatter 

 and more asterigerine* state than those figured by Lamarck. 



* Bearing intercalated imperfect chambers arranged starwise on the 

 umbilical face. 



