Oenus Ovhitoides of d^ OrbiguT/. 447 



le polypier se divise en deux parties dgales dans le sens de son 

 epaisseur ; l'int«5rieurpr^sente alors des couches d'accroissement 

 et des cercles qui, en se cvoisant, ornent ces lames de losanges 

 disposes en quinconces circulaires. Diam^tre des plus 

 grands individus, 50 millim. ; epaisseur, 3 millim. 



" Les individus jeunes, dont on serrait tentd de faire une 

 esp^ce, sont moins larges, plus eleves, proportion gardde, et 

 ressemblent a deux cones opposes base a base. 



''Cette esp^ce est figuree dans Faujas de Saint-Fond 

 {' Histoire de la Montague de Saint-Pierre de Maestricht, 

 pi. xxxiv. figs. 1, 2, 3, 4). Elle est aussi indiqude, mais non 

 decrite dans le genre discholite de Fortis. 



" Log. de S. Guest. Rojan, Lanquais, Dordogne. 



" Etage 4. 



" Log. du Nord de la France et de V Europe. Maestricht. 



" Etage, Craie tuffau. 



" (Mem. Soc. G^ol. de France, tome ii. 1837. '' Sur la 

 Formation Crdtacee du Sud-ouest de la France,' par M. le 

 Vicomte d'Archiac, p. 178.)" 



With reference, then, to d'Orbigny's illustrations of his 

 Orbiiotdes media, it will be observed that d'Archiac does 

 not mention the central papillary projection represented by 

 d'Orbignyon each side of his specimen (" Profil," /. c), even 

 if his " sillons " be identifiable with the sinuous lines on the 

 surface of d'Orbigny's Orbitoides media, which I much doubt. 

 Nor do d'Archiac nor d'Orbigny notice any granulations on 

 the surface, or the " columns " that extend therefrom to the 

 central plane in the Maestricht fossil^ although both the 

 description of the interior by the former and d'Orbigny's 

 " Coupe horizontale " indicate the structure that is typical of 

 the Maestricht fossil (viz. the " engine-turned " pattern) 

 which Faujas de Saint-Fond has represented in his fig. 4 

 {I. c), as well as of OrbitoUtes Mantelli, Again, while 

 Faujas de Saint-Fond's specimen was only 12 millim., that 

 from the south-west of France described by d''Archiac was 

 50 millim. in diameter. Thus Faujas de Saint-Fond's species 

 of 1799,'d'Archiac's of 1837, and d'Orbigny's Orbitoides media 

 all differ so far as has been above stated ; but, as I have said, 

 such differences in Foraminiferal species are of doubtful 

 specific value, and the difference in size just mentioned need not 

 be regarded as distinctive any more than the jDvesence or 

 absence of the " columns " in this type of Orbitoid structure, 

 as I have above stated. Thus, after all, each of these three 

 fossils might have been regarded by d'Orbigny as typical of 

 his Orbitoides media, as each possesses the most persistent 



