GENUS ORBITOLITES: 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 be specially 

 distinguished from the large Australian Orbitolite, to which it bears 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 ^Egean specimens (^[ 62.), or in those 

 radial deposits on the surface, which are so common among the Philippine forms 

 (^[ 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 I 

 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 

 Ocbitolite 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. lenticulata 

 of LAMARCK, judging by the figure given of it by LAMOUROUX*, is not an Orbitolite, 



* Polypiers, pi. 72. figs. 13, 16. 



