WHAT IS EOZOON ? 83 



unhesitatingly to confirm the sagacious determination of 

 Dr. Dawson as to its Rhizopod characters and Foraminiferal 

 afl&nities, and at the same time furnishes new evidence of no 

 small value in support of that determination. In this exami- 

 nation I have had the advantage of a series of sections of the 

 fo ssil much superior to those submitted to Dr. Dawson ; and 

 ^Hlso of a large series of decalcified specimens, of which 

 ^^■r. Dawson had only the opportunity of seeing a few ex- 

 ^^Kiples after his memoir had been written. These last are 

 peculiarly instructive ; since in consequence of the complete 

 infiltration of the chambers and canals, originally occupied by 

 the sarcode-body of the animal, by mineral matter insoluble in 

 dilute nitric acid, the removal of the calcareous shell brings 

 into view, not only the internal casts of the chambers, but also 

 casts of the interior of the ' canal system ' of the * intermediate ' 

 or ' supplemental skeleton,' and even casts of the interior of 

 the very fine parallel tubuli which traverse the proper walls of 

 the chambers. And, as I have remarked elsewhere,* ' such 

 casts place before us far more exact representations of the 

 configuration of the animal body, and of the connections of its 

 different parts, than we could obtain even from living speci- 

 mens by dissolving away their shells with acid ; its several 

 portions being disposed to heap themselves together in a mass 

 [ when they lose the support of the calcareous skeleton.' 

 I " The additional opportunities I have thus enjoyed will be 

 found, I believe, to account satisfactorily for the differences to 

 j be observed between Dr. Dawson's account of the Eozoon and 

 I my own. Had I been obliged to form my conclusions respect- 

 ing its structure only from the specimens submitted to Dr. 

 Dawson, I should very probably have seen no reason for any 

 but the most complete accordance with his description : while 

 if Dr. Dawson had enjoyed the advantage of examining the 

 entire series of preparations which have come under my 

 own observation, I feel confident that he would have antici- 

 pated the corrections and additions which I now offer. 



"Although the general plan of growth described by Dr. 

 Dawson, and exhibited in his photographs of vertical sections of 

 * Introduction to the Study of the Foraminifera, p. 10. 



