Oenus Orbitoides of d* Orbigny , 449 



in which the specimens of NummuUtes Mantelli of all sizes 

 are abundantly and horizontally imbedded. Size of largest 

 specimens 13^-12ths inch in diameter and l-24th inch thick. 



Loc. Claiborne beds of Alabama, United States North 

 America. 



No. of specimen '' 50515." 



Ohs. In all the Orbitoides there is a marked dijBference 

 between the form of the chambers of the central plane and 

 those of the crust, which consists in the increasing irregu- 

 larity of the horizontal outline in the latter outwards ; while 

 the chambers in the central part of a vertical section of the 

 central plane present a rectangular form, on account of the 

 section of this part passing through them tangentially. 



Thus it will be seen that the Alabama fossil has no 

 " columns " and possesses a cortical layer, which therefore 

 has a smooth surface, while that of the Maestricht fossil has 

 " columns " with a granulated surface, where the granules 

 represent the outer ends of the columns^ which therefore more 

 nearly allies it to, although it is not identical with, the much 

 larger species, viz. OrhitoUtes Mantelli, Cart., from Nal, in 

 JhalawaUj to which I have alluded, in which the distance 

 between the knobs or granules on the surface and their indis- 

 tinctness, together with the size, seem to ally this species 

 more to Giimbel's ^^ Orbitoides dilata''"' among his Lepido- 

 cyclina {op. cit. p. 139, Taf. iv. figs. 45-47) than any of the 

 rest. 



I cannot say more, however, of his figure representing part 

 of the structure of the central plane of this fossil (viz. fig. 

 46) than that it is almost identical with that given by Car- 

 penter of the Alabama species (' Introduction,' pi. xx. fig. 5) ; 

 for according to the position of the cell and its surrounding- 

 lines 1 learn from my large infiltrated specimen from Sind 

 that it may be at one time circular in outline and at another 

 subcircular, as represented by Carpenter and Giimbel respec- 

 tively, that is, according to the position of the section, wliile 

 the cells in iho, fresh state would appear to be all spheroidal. 



P.S. — I regret to say that in correcting the "proof" of 

 my last paper in the ' Annals,' viz. that containing a descrip- 

 tion of the large variety of OrhitoUtes Mantelli, Cart., var. 

 Theobaldi, from Burma (vol. ii. p. 342, Oct. 1888), there 

 were several errors which, on account of illness at the time, 

 were overlooked, but fortunately none which interfered with 

 the descriptive part of the communication ; still as it is 

 desirable that they should be noticed, I append the following 

 fist :— 



Ann. & Mag. N. Hist. Ser. 6. Vol. ii. 32 



