108 THE CANADIAN NATURALIST. [Vol. ix. 



is apparent from his stating that the proper-wall structure some- 

 times crosses the bands of serpentine and calcite, and also that 

 it presents a series of parallel four sided prisms, whereas, when 

 at all perfectly preserved, it shows a series of cylindical threads 

 penetrating a calcite wall. That some of his specimens have 

 contained the proper wall fairly preserved is obvious from his 

 own figures, in which it is possible to recognize both this structure 

 and chrysotile veins, though confounded by him under the same 

 designation. He objects, somewhat naively, that many of the 

 chambers fail to exhibit this nummuline wall, and that it some- 

 times presents a ragged appearance or is altogether opaque. In 

 point of fact it can appear distinctly, either in decalcified speci- 

 mens or in slices, only when the minute tubes are filled with some 

 substance optically distinguishable from calcite, or not acted on 

 by dilute acid. When the proper wall is merely calcareotis (and 

 I have specimens showing that it is often in this state, and with- 

 out any serpentine in its pores), its structure is ordinarily 

 invisible, and it is the same when the calcareous skeleton has 

 from any cause lost its transparency or has been replaced by 

 some other mineral substance. Even in thickish slices, the 

 tubes, though filled with serpentine, may be so piled on one an- 

 other as to be indistinct. All this may be seen in Tertiary 

 NummuJites. When wholly calcareous their tubulation is often 

 quite invisible, and when imperfectly injected with glauconite or 

 other silicates, they often present a very irregular appearance. 

 If Professor Mobius will study the Nummulites injected with 

 glauconite from Kenipten,* Bavaria, in addition to the casts of 

 PolystomeUa from the ^gean to which he refers, he will be 

 better able to appreciate these points. It may be worth repeat- 

 ing here that, in examining the original specimens of Eozoon, I 

 did not recognize the proper wall. I did not doubt that it must 

 have existed in some form, since I could easily detect the canals 

 in the supplemental skeleton ; but I did not wonder at its non- 

 appearance, knowing the chances against its preservation in a 

 recognizable form. Its discovery was due to the subsequent 

 investigations of Dr. Carpenter. f 



* I am indebted to Dr. Otto Hahn for specimens of these most in- 

 teresting fossils. 



f It may deserve mention here that the Carboniferous Fusulina 

 very rarely shows its tubulated wall, and that Dr. Carpenter had 

 maintained its NKmmuline aftinites before lie obtained specimens 

 showing this particular structure. Structures so delicate as these 

 are indeed only preserved exceptionally in fossil specimc'us. 



