4<M NATURAL SCIENCE. June, 1895. 



prepare. The matrix of some of these is composed almost entirely of 

 white pyroxene. 



We understand that further information will be published shortly 

 in relation to the mode of occurrence of some of the typical Canadian 

 Eozobns, and that this is far more in agreement with the theory we 

 proposed than with that of the organic origin of Eozobn. 



Our specimens show both the silicate bands and the calcite bands 

 as lenticular, as in Figs. 1 and 3 (especially at top and right side of 3), 

 pi. xxx. In pi. xxxiv. the silicate laminae are distinctly lenticular and 

 are interrupted. In many of Carpenter's specimens the silicate bands 

 are certainly continuous, and the calcite bands lenticular and inter- 

 rupted. 



The mammillation of the chambers in the Canadian Eozobn is 

 observable with the serpentine, but not with the so-called malacolite 

 bands, and is simply due to an arrangement commonly assumed by 

 amorphous serpentine. 



As to the shape of masses of Eozobn we can place at Sir William 

 Dawson's disposal a great variety, and we could have devoted a 

 hundred pages to descriptions of variations both in shape and 

 structure ; but space and the patience of our readers forbade. Both 

 of us have had some practice in the examination of organic and 

 mineral structures under the microscope, and can appreciate the 

 resemblances and differences between them. Of the two, some of the 

 Vesuvian specimens far better mimic organic structure than do those 

 we have seen from Canada. 



Sir William Dawson tells us that Dr. Carpenter fully understood 

 the differences between the chrysotile veins and the proper wall. He 

 certainly did maintain this view for about twenty years, but then he 

 admitted that he had been in error, and in the last published state- 

 ment of his that we know, he accepted the proper wall as inorganic. 



Sir William Dawson's memory has failed him, for the first author 

 of the paper did show him some specimens when in Naples over a 

 decade ago ; but his suggestion as to their nature was so peremptorily 

 dismissed that he feared to push the matter further, more especially 

 as then no microscopic or even detailed examination had been made. 



Neither of us wish to deny the existence of life in pre-Cambrian 

 times ; though we doubt whether all the cases quoted by Sir William 

 will be verified by further research. 



Finally, when Sir William Dawson denies that the specimens we 

 described " resemble either in composition, mode of occurrence, or 

 form or structure, the Laurentian Eozobn of Canada," we would only 

 remark that when one of them was shown to the only geologist in 

 England whom we could find who still had any faith in Eozobn^ he 

 declared it was an excellent specimen of the Laurentian Eozobn of 

 Canada ; and when he was told it came from Monte Somna he 

 rejected the idea with scorn, and said that if it had, it had been 

 first carried there from Canada. H. J. Johnston-Lavis. 



J. W. Gregory. 



