PETROGRAPHICAL EVIDENCE IN SOUTH INDIA. 235 



Similar bodies, with fine ruby-red corundum, have recently been 

 found near the margin of the Bargur charnockite mass at Badavadi in 

 the Mysore State (u°5o; 77°6'). 



A distinction must of course be drawn between inclusions of 



older foreign rocks which bear no family resemblance to the rocks 



Xenoiiths and' by which they have been picked up, and the 



schlieren (autoliths). .,. , 1* i_ • •» 1 • 1 i> t 



schlieren (generally basic) which are formed 

 by segregative processes during the consolidation of the rock, and 

 which always present some signs of relationship to the rock in which 

 they appear to be included. It is with the former bodies,, xenoiiths 

 as Sollas 1 aptly calls them, that we have to deal with now; the 

 others are discussed on another page (217). 



These corundiferous bodies were originally described by Middle- 

 miss as local modifications of the " biotite 



Corundiferous xenoiiths. 110 ^ 



gneiss " in which they are included. 2 Subse- 

 quently the same author mentioned the hypersthene which occurs 

 with the biotite in this gneiss, and then so far modified his previ- 

 ous nomenclature as to regard the rock as a passage form between 

 the ordinary charnockite series and the Hosur biotite-gneiss. 3 In 

 another section of this memoir I have given my reasons for con- 

 cluding that the rock in which these corundiferous bodies occur 

 is in no genetic sense related to the Hosur biotite-gneiss, but is a 

 normal member of the charnockite series, the prevalent form belong- 

 ing to the " intermediate " type. 



The ellipsoidal bodies are not, in my opinion, the results of 

 mere re-arrangement and alteration of the minerals composing 

 the rock in which they occur, but on the contrary are composed of 

 totally distinct minerals, possess an altogether foreign structure 



1 Trans. Roy. It. Acad., Vol. XXX (1894), p- 493. Inclusions of rocks similar, and perhaps 

 related genetically to the rock in which they are included, Lacroix proposes to distinguish as 

 homogeneous {Enclaves hom&ogenes); but the peculiar meaning we generally attach to homo- 

 geneous prevents our adoption of Lacroix's expression. The word autolith, in contradistinc- 

 tion to xenolith would have been a better term than homogeneous inclusion. 



2 Rec. Geol. Sur. Ind., Vol. XXIX (1896), p. 44. 

 s Ibid., Vol. XXX (1897), P- 119. 



( 117 ) 



