324 Mr. H. J. Carter on the Structure of the Foi'aminifera. 



in the transverse section with certainty, though I have not yet 

 succeeded in making a preparation to show them so satisfactorily 

 in the transverse section (nor can they be demonstrated either 

 in the horizontal or transverse section in fossil Operculina under 

 the most favourable circumstances, although they no doubt did 

 exist there, any more than in Nummulites), it is not to be won- 

 dered at that they should not be demonstrable in Nummulites, 

 where crystallization and fossilization must have more or less 

 blended these structures into one mass. Bat, with the surface- 

 identity mentioned, the presence of the planes of opake matter 

 in the transverse section of the cord (which represent the planes 

 of spicules in Operculina arabica), divided partially at short in- 

 tervals by transverse constrictions (which in Operculina define 

 the ends of the spicules), and the transparent planes or intervals 

 in which arc seen the truncated ends of the great horizontal 

 canals of the canal-system in recent Operculina, I think we 

 have here quite sufficient to enable us to infer that the cord in 

 Nummulites was generally of the same composition as that of 

 Operculina arabica, but with the spicules much longer; that is 

 to say, that the cord was composed of the same kind of materials : 

 viz. 1st, the crystalline matter of the spicules; 2nd, the inter- 

 spicular substance; and 3rd, the canal-system. To arrive at this 

 conclusion, however, it is necessary to be first well acquainted 

 with the spicular cord in recent Operculina, then to compare 

 this with fossil Operculina, and lastly, to compare the latter with 

 Nummulites, all of which must be in specimens favourable for 

 the purpose, — since a mere section of the cord of Nummulites 

 would inevitably be met with a denial of its spicular composi- 

 tion, so little appearance is there in it of spicules. 



Moreover, the " great spiral canals " of the cord of Operculina 

 arabica, to which I have alluded at the commencement, and 

 which are evident also in the cord of N. Ramondi (though not 

 so evident, if existing at all, in N. sublcevigata), did not escape 

 the penetrating and sagacious observation of the authors of the 

 "Fossiles de l'Inde;" for they, as I have previously shown, not 

 only figure the openings of the marginal plexus, but also the 

 two great spiral vessels of the cord in N. planulata, and describe 

 them in the words which have been already quoted. 



Yet, in their work, MM. d'Archiac and Haime have stated 

 (p. 54), " Nous nous sommes assures, par des observations tres 

 multipliees, que dans aucune des especes de ce dernier genre 

 iNummufites] il n'existe rien qui puisse rappeler la corde spicu- 

 lairc ni le plexus marginal signales par M. Carter dans POper- 

 culine d' Arabic" Had the lamented naturalist whose name is 

 last mentioned been alive, he, with his noble colleague, would 

 now have admitted that what I stated, and showed in a figure, 



