Correspondence — Prof. T. G. Bonney — Dr. Joh. Chr. Moberg. 47 



PYROXENE AND SERPENTINE IN ASSOCIATION WITH EOZOON 



OANADEXSE. 



Str, — I fear that in my short notice of the rock containing Eozoon 

 at Cote St. Pierre, which was printed in last year's Volume (p. 292), 

 I must have failed in clearness of expression, since my friend 

 Sir William Dawson, in his interesting defence of " the animal 

 nature of Eozoon," says (p. 505) there " seems to be nn good 

 evidence that any portion of the pyroxene has been changed into 

 serpentine." But of that, as I endeavoured to intimate on parts 

 of pages 297 and 298, I have as good evidence as is possible. 

 My slices show every stage from an unaltered pyroxene (allied to 

 malacolite) to serpentine. In one slice, where the " canal-system " 

 is well preserved, a few residual bits of pyroxene remain among 

 the serpentine; in all the close resemblance of the silicates indicates 

 an identity of the origin, which can be proved in the case of some. 

 His suggestion that the pyroxene may have originated from local 

 showers of volcanic dust seems to me not very probable. Grains 

 or crystals of pyroxene are, no doubt, ejected in fair abundance 

 from certain volcanoes, but in company with basaltic scoriae. It is 

 difficult to understand how the latter could be sifted from the 

 former, and if this has not been done, what has become of the 

 abundant aluminous silicate ? True, there is a little white mica 

 in the crystalline limestone, but not enough to represent the ash 

 even of a Limburgite. Moreover, I believe the augite of a basalt 

 is generally the aluminous variety. Perhaps, however, he would 

 appeal to an eruptive peridotite. Here almost all the material 

 would ultimately produce serpentine; but, then, volcanoes discharging 

 only olivine augite slag are extremely rare ; indeed, I should hardly 

 like to say as yet, notwithstanding Kimberley, that their existence 

 has been proved. T. G. Bonney. 



SWEDISH GRAPTOLITES. 



Sir, — The November Number of the Geological Magazine 

 contains the conclusion of an English translation of Dr. G. Holm's 

 paper " On Didymograptus, Tetragraptus, and Phyllograptns,'" upon 

 which I trust you will allow me to make the following remarks : — 



Speaking of Isograptns gibbemlus, Nich., sp. (or, as he prefers to 

 term it, JJidymograptus gibbemlus), Dr. Holm quotes a previous 

 paper of mine, in which I have treated of this matter. In that 

 paper I stated in the very beginning, in direct terms, that the fossil 

 in question has two stipes. Further on a sicnlar appendage is 

 mentioned which, at a long distance from the sicula, is not incon- 

 siderably widening. 



Now we have to remark that Hall (in his " Graptolites of the 

 Quebec Group") lias figured some specimens of Tetragraptus Bigsbyi, 

 Hall, so placed on the slab that two stipes are wholly visible, while 

 you can only see the profile of a third. Such a stipe affords some 

 very remote resemblance to the appendage described, and in 

 order to avoid the suspicion that my observations had been based 

 upon specimens preserved in a similar manner, I have appended 

 in a footnote this remark : " Since this dilatation (of the 



