F. Chajyman — TeHianj Foramiuifera in Liinestonea, Sinai. 367 



III. — Tertiary Foraminiferal Lijiestones from Sinai. 



By Frederick Chapman, A.L.S., F.K.M.S. 



(PLATES XIII AXD XIV.) 



[Concluded from the July Number, p. ZIQ.) 



NuMMULiTES, Lamarck [1801]. ' 



Preliminarij remarhs on the genus. — The interesting observations 

 on the dimorphism of the genus NimirnuUtes, which have been made 

 from time to time by special investigators, such as Von Hantken, 

 Munier-Chalmas & SchUimberger, De la Harpe, Rupert Jones, and 

 Van den Broeck, have resulted in the establishment of couples of 

 so-called species, constituting a species in the zoological sense, in 

 which the smaller form, with a large central chamber, is referred 

 to as form A, whilst form B usually has a larger test and invariably 

 possesses a diminutive central chamber. The two forms are other- 

 wise spoken of as the megalospheric and microspheric forms. In 

 some cases there may be little doubt as to the accuracy of the 

 assignment of the two forms to one species, especially since they 

 may be the only examples present in the rock. In the case of 

 a stratum containing more than two species, however, there may 

 be no small difficulty in coupling the actual forms which constitute 

 the species, for there is often little in either the internal or external 

 characters to guide one in linking the forms. In our present state 

 of knowledge, therefore, it appears to be most convenient to describe 

 the forms under their, specific denominations as already known, at 

 the same time pointing out their relationship to one another. Some 

 good suggestions as to the naming of Nummulites and other 

 Foramiuifera which exhibit the two modes of growth and shell 

 form have lately been made by Dr. A. Silvestri.^ 



With regard to the older method of grouping the Nummulites 

 according to their superficial appearance and texture, this can be 

 at the best only an artificial method of arrangement, for it some- 

 times happens that two different forms constituting a zoological 

 species may be found to belong to two of the separated so-called 

 groups ; as, for instance, N. cnrvispira, which has been placed in the 

 granulate group, and N. complanata or N. complanata, var. PacJioi, 

 in the group of smooth forms. Moreover, it will be seen by 

 referring to Eupert Jones' Catalogue of Fossil Foramiuifera in the 

 British Museum,- that N. cnrvispira is an example of the granulate 

 group which does not invariably exhibit the characters ascribed to it. 



Nummulites pjlnnulata (Lamarck). (PI. XIII, Fig. 2a.) 

 Lent'tmlites pUnulata, Lnmarck, 1804: Anuales dvi iluseura, vol. r, p. 187. 

 Nummulites pUnulata (d'Urb.), d'Archiac & Ilaime, 18o3: Descr. Auiin. groupo 

 nunimulitiquo Inde, vol. i, p. 142, pi. ix, figs, ha, 6«-c, la-h, Sa~d, 

 9a, b, 10«-c. 



One recognizes this form by the minute or almost invisible central 

 chamber, and the flatness of the test. In section it exhibits from 



1 Atti dell' Accad. Pont. Nuovi Liucei, Anno liii (1900), pp. 1-10. See also 

 Van den Broeck : Bull. Soc. Beige Geol. Pal. Hvdr., vol. x (1896), 1899. 

 • Op. cit., pp. 46, 47, specimens P 1014 and'P 890. 



