1865.] CARPENTER — STRUCTURE OF EOZOON. 115 



(plate, figure 3. c) ; and I think it likely that I should have 

 been able to trace it at its other extremity into a chamber of the 

 superjacent tier, had not the plane of the section passed out of its 

 course. Riband-like casts of these passages are often to be seen 

 in decalcified specimens, traversing the void spaces left by the re- 

 moval of the thickest layers of the intermediate skeleton. 



But the organization of a new layer seems to have not unfre- 

 quently taken place in a much more considerable extension of the 

 sarcode-body of the pre-formed layer ; which either folded back its 

 margin over the surface already consolidated, in a manner somewhat 

 like that in which the mantle of a Cyproea doubles back to deposit 

 the final surface-layer of its shell, or sent upwards wall-like la- 

 mella), sometimes of very limited extent, but not unfrequently of 

 considerable length, which, after traversing the substance of the 

 shell, like trap-dykes in a bed of sandstone, spread themselves out 

 over its surface. Such, at least, are the only interpretations I can 

 put upon the appearances presented by decalcified specimens. For 

 on the one hand, it is frequently to be observed that two bands of 

 serpentine (or other infiltrated mineral), which represent two layers 

 of the original sarcode-body of the animal, approximate to each other 

 in some part of their course, and come into complete continuity ; so 

 that the upper layer would seem at that part to have had its origin 

 in the lower. Again, even where these bands are most widely sepa- 

 rated, we find that they are commonly held together by vertical 

 lamellae of the same material, sometimes forming mere tongues, but 

 often running to a considerable length. That these lamellae have 

 not been formed by mineral infiltration into accidental fissures in 

 the shell, but represent corresponding extensions of the sarcode- 

 body, seems to me to be indicated not merely by the characters of 

 their surface, but also by the fact that portions of the canal-system 

 may be occasionally traced into connection with them. 



Although Dr. Dawson has noticed that some parts of the sections 

 which he examined present the fine tubulation characteristic of the 

 shells of the Nummuline Foraminifera, he does not seem to have 

 recognized the fact, which the sections placed in my hands have en- 

 abled me most satisfactorily to determine, — that the proper walls of 

 the chambers everywhere present the fine tubulation of the Nummu- 

 line shell (plate, figs. 3, 6) ; a point of the highest importance in 

 the determination of the affinities of Eozoon. This tubulation 

 although not seen with the clearness with which it is to be discerned 



