INTRODUCTION. 



memoir, of which the paper tinder notice is an " abstract." 

 The latter notices the occurrence of "beautiful examples of ' canal 

 system/ resulting from the waste of crystalloids of malacolite, in 

 the calcaire saccharo'ide (hemithrene) of St. Philippe (Vosges)-, 

 rivalling those in Canadian ophite." 



When speaking of this hemithrene (pp. 51, 52) we omitted to 

 mention that, besides the " canal system," there are also present 

 rounded grains or crystalloids of pyrosclerite (a serpentinous 

 mineral), occasionally invested with an asbestiform mineral 

 related to, if not identical with, chrysotile : the investing fibres, 

 usually in contact, are in many places separated by interpola- 

 tions of calcite (PI. III. figs. 2, 3), a fact proving them to corre- 

 spond with those of the "proper wall" of "Eozoon Canadense." 



Mobius on Eozoon Canadense. Dr. J. W. Dawson. American 1879. 



Journal of Science, March 1879. 



The writer, as must have already been noticed (A.D. 1876), 

 is evidently anxious to make out that there is no necessary 

 connexion between serpentine and " Eozoon" This anxiousness 

 seems to have developed itself apace ; for he now asserts that 

 " only a few " geologists and mineralogists " have learned that 

 Eozoon is only sometimes associated with serpentine " ! Totally 

 dissenting from such an assertion, we beg to draw Dr. Dawson's 

 attention to the fact, which ought always to be uppermost in his 

 mind, that " Eozoon " is mostly present in metamorphic rocks, 

 especially ophicalcif es and hemithrenes (the product of chemical 

 changes), and is "best preserved in those that are highly crys- 

 talline." And by way of invalidating Dr. Dawson's assertion, we 

 challenge the production (allowing certain exceptions, which are 

 explainable) of an indisputable specimen of <f Eozoon " with its 

 "chambers," "canal system, and "proper wall" ("tubuli"), 

 preserved otherwise than in serpentine or a serpentinous 

 mineral. We admit occasional exceptions, because the mineral 

 silicate forming these features is replaceable by calcite. 



Dr. Dawson refers to the " cumulative force " of the eozoonal 

 structures " when taken together. In this aspect, the case of 



