GENUS ORBITOUTES: — SPECIES. 
225 
basin, I have made investigations scarcely less minute and extended than into that 
of the recent forms ; and I have come to the conclusion, that it cannot he specially 
distinguished from the large Australian Orbitolite, to which it hears a very obvious 
general conformity. It is true that it differs from the typical forms of the latter in 
two important features of structure, which are, however, mutually connected ; — 
namely, the direct continuity of the cells of the superficial layers with the columnar 
cells of the intermediate layers ; and the rounded or ovoidal form of the superficial 
cells, which (as already stated) these always possess, as in the simpler type, unless 
they are disconnected with the columnar cells, and communicate only with the 
annular stolons (see 58.). But since this very peculiarity does present itself in 
certain existing individuals, whose development seems to have taken place upon a 
lower type, and since it occasionally shows itself in the course of the passage from 
the simplest to the most complex type, in such as ultimately attain the latter, there 
appears to me no room for questioning the specific identity of the O. complanata with 
the Australian forms, notwithstanding that I have never met, among the numerous 
specimens which I have examined of the former, with those elongated parallel-walled 
superficial cells, which constitute the most distinctive feature in the latter. It may 
be well, moreover, to bear in mind the remark I have already made, respecting the 
local prevalence of particular varieties of form ; since there is nothing more strange 
in the incompleteness of the type of development presented by the Paris-basin Orbi- 
tolite, than in that tendency to excessive development, which gives rise to the nume- 
rous monstrosities that are presented by the iEgean specimens 62.), or in those 
radial deposits on the surface, which are so common among the Philippine forms 
(H 53.). My belief in the specific identity of this fossil with the recent types has 
been strongly confirmed by the circumstance, that among the Paris-basin forms 1 
have found a minute specimen, which corresponds in every respect with the simple 
type of the existing species. 
70. Of the other fossil species cited by Lamarck, the O. macropora of the Maes- 
tricht beds, judging from the figure given of it by Goldfuss, is nothing else than an 
Orbitolite of simple type, whose marginal cells have been laid open by attrition both 
above and below, as in Plate VII. figs. 8, 10. The O. concava and O. pileolus of 
Lamarck are not distinguished in his definition by any other character than that 
drawn from form, which we have seen to be so variable as to be quite insufficient as 
a distinctive feature. It is quite possible, moreover, that they may belong to another 
type, nothing being said in the description of them, either of concentric lines, or of 
pores. If, as I believe, the O. concava of Lamarck (figured by Michelin in his 
‘ Icon. Zoophyt.,’ pi. 7- fig- 9) be identical with the O. conica of M. d’Archiac, I feel 
certain (from careful examination of its imperfectly-preserved internal structure) 
that, whatever it may prove to be, it is not an Orbitolite. So again, the O. lent'icidata 
of Lamarck, judging by the figure given of it by Lamouroux*, is not an Orbitolite, 
* Polypiers, pi. 72. figs. 13, 16. 
