Nomenclature of the Foraminifera. 37 
the newest or outermost annuli. Bronn, op. cit. p. 86, errs in 
describing the apertures or pores as being on the edge of the last 
chamber. The septa of the annular chambers are limbate ; but 
the secondary or cross septa (though probably present) give no 
evidence of their existence. This absence of limbation of the 
secondary septa is such as occurs in certain specimens of Or- 
bitolites. 
Orbitolina discoidea, Gras (Foss. de l’Isére, p. 52, pl. 1. f. 7-9), 
is a thick flat form ; and possibly Orbitolites plana and O. ma- 
millata, D’ Archiac (Mém. Soc. Géol. France, ii. p. 178), may also 
be Orbitoline of the same character. D’Archiac’s Orbitolites 
media (op. cit. p. 178), placed by D’Archiac and Bronn with O. 
Faujasti, is an Orbitoides, as 1)’Orbigny has indicated. The 
last, however, mistook O. Faujasii for an Orbitoides. 
D’Orbigny’s species O. radiata (Prod. ii. p. 280), from Royan, 
is not well characterized. There are many radiate and stellate 
Foraminifers in the Maestricht Chalk and the Nummulitic Ter- 
tiaries which may be either Orbitoline, Orbitoides, or Calcarine. 
The radiate ridging of the surface would not be a feature at 
variance with the growth and habit of Orbitolina. We have not 
yet, however, sufficient means of comparison to be satisfied as to 
the relations of the forms referred to, although we believe them 
to be Calcarine. 
With regard to the relationship of Orbitolina to Orbitoides, 
we may say that they have the same structure, as far as the cell- 
growth and the interstitial substance* are concerned ; but Ordi- 
toides is always subsymmetrically discoid, or lenticular, heaping 
cells on both faces of its primary, annular, subdivided chambers ; 
whilst Orbitolina, which has one symmetrical variety, has many 
that have no pretence to bilateral symmetry, any more than the 
conical Rotalie, and, in its typical concavo-convex form, it 
bears the same relation to Orbitoides that Rotalia does to Num- 
mulina. The umbilical growth of irregular and imperfect cells 
in Orbitolina is a feature similar to the astral formation of the 
divided umbilical lobes of the chambers in some Rotalie (for 
instance, Asterigerina lobata) ; and we may say that Orbitolina 
has the same relation to Rotalia that Cycloclypeus has to Num- 
mulina,—Williamson’s Patellina representing Heterostegina. 
The following are the most important varieties of Orbitolina 
concava, Lam. :— 
1. Orbitolina simplex, P. & J. _—‘ Tertiary : Grignon. 
seailousolars: Psd. Recait Fadia Ocean. 
* The limbation, arising from septal granulation, of the stellate Orbito- 
line from New Zealand and Fiji, and of the conical specimens from Ciply, 
is not unlike that of some of the Orbitoides of the Maestricht Chalk. 
