WHAT IS EOZOON I 



87 



glistening fringe ; and when this fringe is examined with a 

 sufficient magnifying power, it is seen to be made up of a 

 multitude of extremely delicate aciculi, standing side by side 

 like the fibres of asbestos. These, it is obvious, are the inter- 

 lal casts of the fine tubuli which perforated the proper wall of 

 le chambers, passing directly from its inner to its outer 

 inrface ; and their presence in this situation affords the most 

 itisfactory confirmation of the evidence of that tubulation 

 forded by thin sections of the shell-wall. 

 "The successive layers, each having its own proper wall, are 

 )ften superposed one upon another without the intervention of 

 mj supplemental or intermediate skeleton such as presents 

 itself in all the more massive forms of the Nummuline series ; 

 mt a deposit of this form of shell-substance, readily dis- 

 |;inguishable by its homogeneousness from the finely tubular 

 jhell immediately investing the segments of the sarcode-body, 

 the source of the great thickening which the calcareous 

 sones often present in vertical sections of Eozoon. The pre- 

 sence of this intermediate skeleton has been correctly indi- 

 ited by Dr. Dawson ; but he does not seem to have clearly 

 lifferentiated it from the proper wall of the chambers. All 

 the tubuli which he has described belong to that canal system 

 '^hich, as I have shown,* is limited in its distribution to the 

 Ltermediate skeleton, and is expressly designed to supply a 

 jhannel for its nutrition and augmentation. Of this canal 

 [system, which presents most remarkable varieties in dimen- 

 [sions and distribution, we learn more from the casts presented 

 )y decalcified specimens, than from sections, which only 

 exhibit such parts of it as their plane may happen to traverse. 

 [Illustrations from both sources, giving a more complete 

 representation of it than Dr. Dawson's figures afford, have 

 [been prepared from the additional specimens placed in my 

 [hands. 



It does not appear to me that the canal system tak.es its 



J origin directly from the cavity of the chambers. On the con- 



^trary, I believe that, as in Calcarina (which Dr. Dawson has 



jorrectly referred to as presenting the nearest parallel to it 



* Op. cit,, pp. 50, 51. 



