Mr. H. J. Carter on the Structure of the Foraminifera. 315 



test ? And could the horizontal layers of the test be formed in 

 any other way, or are they likely to be so, under such circum- 

 stances ? Lastly, is not all this in favour of what I have stated, 

 viz. that there is a substance in appearance like the "cuticle" 

 of shells, over the dried specimens of Foraminifera which con- 

 tained the living organism when they were taken out of the water ? 

 But, as I have already observed respecting the spicular structure 

 of the cord, the fact does not rest upon argument, but can be 

 demonstrated; and upon demonstration I made the statement 

 ten years ago ! 



The "vertical tubuli," as just stated, connect the chambers 

 with the surface, not only in Operculina, but in the tests of 

 Nummulites, Orbitoides dispansa, and Orbitolites Mantelli ; and 

 it is through their agency chiefly that the layers of shell and the 

 chambers are vertically formed. 



The openings on the horizontal surface over and about the 

 septal spaces are those of canals connected with the great inter- 

 septal system. They are the same as MM. d'Archiac and 

 Haime's "canaux d'une troisieme grandeur," or middle-sized 

 canals." 



But, besides these openings, there are spaces and lines in 

 Operculina which are composed of shell-substance alone, that is, 

 without the presence of the vertical tubuli or the middle-sized 

 canals ; and these in the test of the recent Operculina have the 

 appearance of homogeneity and transparency, but are opake and 

 white in the fossilized one, where they evidently are identical 

 with the opake-white portions of Nummulites, which have af- 

 forded MM. d'Archiac and Haime some of their chief distin- 

 guishing characters ; and thus the latter are proved not to be 

 what they supposed them, viz. remains of " larges canaux," but, 

 originally, transparent portions of the shell, unaccompanied by 

 any canal, except accidentally, as will be more particularly shown 

 hereafter. 



Animal of Operculina. — Hardly anything more of the animal 

 of Operculina is known now than when my description of the 

 test was published ; and I now, as then, cannot help thinking 

 that the existence of the animal matter of the Robulina which I 

 examined at sea, and thought to be in the form of a worm in 

 " loops " in the chambers, united by constrictions where the 

 chambers joined, close to the spicular cord, was a fallacy ; for the 

 observations were made at sea, in a little vessel, on the deck, in 

 the open air, with simple though powerful lenses; and since 

 then, all that I have been able to obtain from the specimens of 

 Operculina which had living animals in them when they were 

 taken, is a number of membranous sacs, corresponding in form 

 with that of the chambers, and united by a like membranous 



