284 Correspondence — Arthur Rowe — A. R. Hunt. 



a decomposition product of other titaniferous mioerals. Professor 

 W. J. Lewis described a large crystal of sartorite from the 

 Binnenthal measuring 4" X 1" X y. An analysis by Mr. Jackson 

 gave the following result : Pb = 42-93, S = 25-32, As = 31-11. 

 Professor Lewis also discussed some peculiar twinned crystals of 

 copper-pyrites and cerussite. Mr. W. B. Giles contributed notes 

 on Howlite and other borosilicates from the Borate mines of 

 California. One of these, for which the author proposes a new 

 name, is a white amorphous mineral resembling in appearance 

 pandermite ; the results of two closely agreeing analyses of 

 material from different localities corresponded to a formula 8 Ca . 

 5 Bj O3 . 6 Si O2 . 6 HgO. Mr. Giles also described a tantalite from 

 Green Bushes, West Australia, which contained 85 per cent, of 

 tantalic with very little niobic acid. Mr. J. Allen Howe exhibited 

 specimens of peculiar pseudo-stalactitic growths of calcite from the 

 North of England. 



00E,i?,Es:P03^iD:Bi<rG:E]. 



THE ZONE OF MICRASTER PRMCURSOR. 



Sir, — On pp. 51 and 54 of " The Geology of the country 

 around Salisbury " (Mem. Geol. Surv., Sheet 298) the term ' zone 

 of Micraster prcecursor ' is used. As one who is not a little interested 

 in the genus Micraster, and more especially perhaps in the group- 

 form which is known as Micraster prcBcursor, I would crave a little 

 information as to the reasons which have guided the author of this 

 memoir in finding a new zonal title. 



Possibly the use of this urchin as a name-fossil is not new, and in 

 that case I must plead guilty to having failed to notice the first 

 occasion of its use. If, on the other hand, this be the first publica- 

 tion in which it has been employed, it would not be unreasonable 

 to expect some statement concerning a fortunately rare event — 

 the adoption of a new name-fossil for one of the zones of the 

 White Chalk. Abthur Eowe. 



1, Cecil Street, Margate. 



Maij 6ih, 1903^ 



SAND-DRIFTING AND SEDIMENTATION. 

 Sir, — I have read Professor Blake's papers on sedimentary deposits 

 with much interest. So far as I can judge, my election to the General 

 Committee of the British Association in 1879 was due chiefly to my 

 work on this subject, and especially to a paper published in 1878, 

 "Notes on Torbay." Such being the case I very naturally made 

 several attempts to elicit discussion in Section C ; but at that time 

 geologists absolutely refused to look at the subject. In 1886 I made 

 a number of special experiments, but the Committee of Section C at 

 Birmingham not only omitted even to include my paper (" Deposition 

 and Denudation, etc.") in the list for reading which was published 

 at that meeting, but for the first time omitted my name from the 

 Committee. Ultimately an influential friend remedied both defects, 

 and I was able to read a six minutes abstract in the subsection on 



