XIV INTRODUCTION. 



" canal system " is paralleled by ramose foliations of metaxite, 

 and is analogous to the coralloids of the magnesian limestone 

 common at Sunderland, that the ' ' proper wall " is a modifi- 

 cation of chrysotile, in short, that all the features diagnosed for 

 Eozoon are of purely inorganic origin, resulting from chemical 

 and structural changes in the minerals severally composing them. 



Previously to the publication of our paper no reference had 

 been made by Logan, Dawson, Carpenter, Sterry Hunt, or 

 Rupert Jones, in their respective writings on " Eozoon/' to the 

 presence of chrysotile in frequent association with this presumed 

 fossil. In fact, serpentine in all its forms and relations was 

 altogether ignored. 



At the time referred to, the subject of mineral pseudomorphism 

 was in an extremely unsettled state. The opinion respecting it, 

 as advocated by Blum and others, was being opposed by Scheerer, 

 Naumann, and Delesse, and especially by Sterry Hunt, who was 

 enthusiastically propagating his " novel doctrine " the chemical 

 precipitation of metamorphic rocks ; so that the obvious facts 

 connected with eozoonal features escaped being sufficiently 

 examined from a mineral point of view. Moreover the origin 

 of serpentine, one of the metamorphics in question, was equally 

 a bone of contention its protean character, both structural and 

 chemical, its occurring indifferently as intrusive dykes and sedi- 

 mentary beds, its playing a prominent part in what was taken 

 to be the earliest sea-born organism of our planet, and the little 

 then known with respect to chemical changes in rocks, all taken 

 together, caused mineral pseudomorphism to be thrown into the 

 background to be repudiated as having any thing to do with 

 the " creature of the dawn." 



In addition to other points introduced by Dr. S. Hunt in his 

 memoir of 1864, and which are duly noticed in the following 

 pages, he describes the mineralogy of "Eozoon" from one of the 

 specimens which first led Logan to suspect their organic 

 origin. A specimen of the kind has been lately sent (April 1881) 

 to us by Mr. R. Damon, F.G.S., who received it from Dr. 



