ccii Journal of the Asiatic Society of Bengal. [X.8.. XIII, 



I do not propose to go further than this, anil it is certainly not my 

 intention in any way to suggest that the Mysore Department should 

 immediately proceed to revise their conceptions regarding the origin of 

 the rocks of their own extremely interesting country ; but I do urge that 

 all the pros and cons in the case should be very carefully and patiently 

 considered, as I have no doubt that they certainly will be. 



Chamberlin and Salisbury have written as follows in their Geologv, 

 p. 429 (1905), under the heading of " Completion of the Rock Cycle " :— 



"The crystallising processes of metamorphism are fundamentally 

 -imilar to the processes by which rocks crystallise out of magmas, 

 only in the first case the work is done chiefly by the aid of an aque- 

 ous solution, while in the second it is done through the mutual solu- 

 tion of the constituents in themselves where water was but an inci- 

 dent. If the heat factor in metamorphism be sufficiently increased, 

 aqueous solution may actually grade into magmatic solution through 

 various degrees of softening and melting, and the cycle of change 

 be closed in upon itself." 



Consequently, it seems to me, that in dealing with any rock that 

 appears to be of doubtful igneous or magmatic origin, it is above all 

 necessary ln these days to ascertain in which direction the cycle of change 

 is moving. To put the matter bluntly— an apparent ortho-gneiss with its 

 contemporaneous veins may quite as well be an intensely metamorphosed 

 sediment with pegmatites formed in it by ' selective solution ' as it may 

 be the extreme, fohated or otherwise modified, representative of a grani- 

 tic, gabbroid or hybrid abyssal injection. 



Notes on the Origin of the Living Molluscan Fauna of the 

 Indian Ocean, with reference to Former Geological Times. 

 — By E. Vredenburo. 



The object of this paper is to show that most of the genera and 

 species characteristic of the Indian or Indo-Pacific region at the present 

 day have originated in that same region in former geological times ; and 

 S;^ Pf vlou / u § eol °g^al periods, the fauna of the Indo-Pacific region 

 ,fZ L^T ?* ° f th f ^ tlantic and Mediterranean very much in the 

 eXnf^f^V .° eSa *, the , presentda y- Xt als ° *howJ that during 

 more Si ect ZT P er f lod \ of wid <* marine extension, when there was a 

 Till ™ °TT ,Catl ° n betW6en the Indian and Atlantic regions than 

 butLt FhZ ' there / ere so ™ exch *nges between the two faunas, 

 rectfon or Z M™ ^T u° f S y im P orta n* migration either in one di- 

 Se insufficS V tH if Shght u diluti0n of one fauna with the other being 

 two regions ** ^ well '»«k«d faunistic differences of the 



A preliminary note on the Origin of Wolfram-bearing Quart/ 

 Brown 111 7 District ' Lo ^r linrma -«, J Ooggin 



and ^author Zl^T^ '^^ ° btained U P to the P«*»* tirae ' 

 The wolfram dloS^h ^^ ° f 0ther work « rs on sim ilar deposits. 



eo* e^VSSauT Z£° V f t0 °u riginate fr ° m ^ liartZ l0d6S 

 the ancient sediment! • P 6S ' etc -' Wlth g™nite masses penetrating 



occa^onaUv conT« 2« 7 T™ Un ? wn as the Mer g ui *»*». The granite 

 and Xtz St ? °^ *** mol y b denite, and the pegmatite dykes 

 •^SS^WSlSXa^^ -lybdenum^smuth. iron, 



wo Jam aS^in £d« ^V* 1 ^^ Dr. Bleeck's theory concern.ng the 



" mineraUone » a Zu ^° Y ' e *P eda »y as to the presence of a distinct 



merai zone, a "olfram.te-cassiterite-colnmbite Z one and the presence 



