INTRODUCTION. XXlfi 



Prof. Hull. Quart. Journ, of Science, July 1869. 



" The researches of Sir William Logan and his colleagues of 

 the Geological Survey of Canada, followed by other naturalists, 

 have demonstrated that even the oldest known limestones on 

 the surface of the globe owe their origin to Eozoon." 



On "Eozoon Canadense." Drs. King and Rowney. Proc. Roy. 1869, 

 Irish Acad. vol. x. pp. 506-550. 



Notices the Tudor specimen, which, Dr. Dawson asserted 

 (A.D. 1866), " furnishes a conclusive answer to" our "objec- 

 tions." But, from the description (amply discussed in the 

 memoir) and photograph given of it, we express " little doubt 

 of its being any thing more than the result of infiltration of 

 carbonate of lime, which has penetrated into a parting between 

 two layers of laminated arenaceous limestone " an opinion 

 which remains neither controverted, nor even invalidated, 

 though attempts have been made to do so. 



The "cumulative" argument advanced, but not clearly ex- 

 pressed, by Dr. Carpenter (A.D. 1866) is discussed. It may 

 now be mentioned that the fact of different eozoonal structures 

 being often found in association must be held as a proof of 

 their mineral origin, inasmuch as the mineral silicates com* 

 posing them are in pseudomorphic correlation; while the 

 calcite and miemite (either of which constitutes the "inter- 

 mediate skeleton") are not only pseudomorphous after these 

 silicates, but they stand in the same relation to each other. 

 The "cumulative" argument is thus totally invalidated by 

 purely chemico-mineralogical phenomena. Besides, Dr. Car- 

 penter in advancing it has placed himself on the horns of 

 a dilemma; for he is required to explain the occurrence of 

 different eozoonal structures by themselves in widely separated 

 countries. The "intermediate skeleton" includes the "canal 

 system" and "proper wall." How does it happen that the 

 last feature is absent in the eozoonal hemithrenes of Finland, 

 Saxony, and Ceylon, and only the former one present? Why 



