On the Nomenclature of the Foraminifera. 29 



VIII. — On the Nomenclature of the Foraminifera. 

 By W. K. Parker, M. Micr. Soc., and T. R. Jones, F.G.S. 



[Continued from vol. v. p. 477«] 



32. Orbulites marginalis. Hist. An. s. Vert. ii. p. 196, No. 1. 

 " Recent ; European Seas ; discovered by M. Sionest on Coral- 

 lines, Fucus, &c." 



Under this name Lamarck placed the living European Orbi- 

 tolites, which, though smaller than the fossil specimens from 

 Grignon (and than the Australian and South Sea individuals), 

 doubtless belong to the same species, O. complanata. 



33. Orbulites lenticulata. Hist. An. s. Vert. ii. p. 197, No. 3. 

 " lentiformis, superne convexa, subtus planiuscula. Habite, 

 — se trouve fossile k la Perte du Rhone, pres du Fort de PEcluse, 

 k huit lieues de Geneve. Elle y forme des masses considerables. 

 M. Brard. Mon cabinet." 



According to Bronn, this fossil was named Madreporites lenti- 

 cularis by Blumenbach, 1805, Naturhist. Abbild. Nr. u. Fig. 80. 

 It has been recognized by D'Orbigny as a Foraminifer. In his 

 'Cours Elem/ ii. p. 193, and 'Prodrome/ ii. p. 143, he gives it 

 the generic name of Orbitolina, and regards it as " an unsym- 

 metrical Orbitolites coated with encrusting cells on one side." 

 This we do not accept as a correct definition of its relationship. 

 Our views of the structure and relationship of this form will be 

 best understood if we trace it from its simplest variety to its 

 highest state of development. It is among both recent and 

 fossil specimens, from many parts of the world, that we collect 

 our materials for the elucidation of this protean and hitherto 

 misunderstood Rhizopod. 



1. Among the abundantly varied Foraminifera from the Ter- 

 tiary beds of Grignon we find a very minute, smooth, scale-like 

 shell (about yj^ inch in diameter), thin, transparent, and sparsely 

 perforate, and consisting of a circular, subconical, tent-like top 

 covering one or two relatively large subannular chambers, which 

 are not distinctly separate. 



Seen from below, these chambers, occupying the greater part 

 of the hollow of the tent or shield, present a convex aspect, with 

 a central pit or umbilicus, — the outer and lower, or marginal, 

 portion of the shield bearing very slight indications of annular 

 septal markings, left probably by the sarcode that occupied the 

 concavity. 



Seen from above, or from the side, this little subconical shell 

 presents (by transparency) faint appearances of three whorls of 

 a spire due to the first and second cells (the latter being some- 

 what semilunar) and the outer rudimentary septum. We name 

 this variety Orbitolina simplex. 



