Mr. H. J. Carter on the Structure of the Foraminifera. 327 



columnar structure^ viz. the " larges canaux " of D'Archiac and 

 Haime, is particularly developed in the reticulated Nummulites, 

 and is analogous to that of 0. dispansa, although not so much 

 developed. But, as will be seen by-and-by in Orbitoides, the 

 rows of chambers in the horizontal plane are cyclical, which is a 

 character of Orbitolites, and not of Nummulites. This, then, 

 makes O. dispansa, although it more than all the other large 

 discoidal Foraminifera approaches the reticulated Nummulites, 

 distinctly differ from them. It will be observed further on, that 

 the structure of Orbitoides dispansa compels us to view it as 

 merely a Cycloclypeus with lateral growth ; and Dr. Carpenter, 

 who has studied the latter, observes (Phil. Trans. 1856, p. 563), 

 that while Cycloclypeus agrees in most points with NummuliteSf 

 it only differs from it essentially "in the single circumstance 

 that the mode of increase is cyclical instead of helical ;" so that 

 we have here still further, though indirect, confirmation of what 

 I have before stated, viz. that N. acuta " borders close upon 

 Orbitoides." As to the defective state of my figures (Ann. Nat. 

 Hist. vol. xi. pi. 7, 1853) misleading the authors of the "Fos- 

 siles de Plnde,^^ it should be remembered that they bear on their 

 faces e\idence that they were only meant as diagrams, and that, 

 in India, we have not only frequently to find the objects them- 

 selves, but to make sections of, and draw them before we describe 

 them, and sometimes to lithograph them ; and therefore that 

 it would be fairest to judge from the descriptions, as they are 

 most likely to be correct, seeing that we have neither such means 

 nor such men to make sections, drawings, &c., for us in India 

 as can be obtained in Europe. 



Alveolina, D'Orb. 



Of this genus I have nothing to state here further than that 

 the tubular cortical structure appears to me to be analogous to 

 the spicular cord and its canal-system in Nummulites, and the 

 chambers to both the horizontal plane and those parts of the 

 chambers which are lengthened out towards the poles or lateral 

 eminences in Nummulites. As before stated, Alveolina looks to 

 me like a flat Nummulite drawn out in each direction laterally, 

 and has its transitional form in the globose Nummulites. Never 

 having had a highly infiltrated specimen, I cannot state what 

 the minute structure of its canal-system is, nor whether the 

 cortical layer, which corresponds to the spicular cord of Num- 

 mulites, contained any spicules; but I should think not, and 

 that the canal-system was replaced by the tubular structure of 

 the cortical layer. As before stated, spherules have been observed 

 in A. elliptica in its innermost chambers. 



The species of Alveolina (viz. A. Boscii) described and illus- 



