124 



E. 0. Teale: 



Here again, hoAv-ever, many more sections require to be ©xaminerP 

 in order to determine whether in their case, as it would seem to- 

 be, the orthockse felspar predominates. 



Chemical Characters aiul Petr&grajyhical Relationshiq)^. — Only a 

 feAT analyses are available, and from a limited area. These are all 

 of the acid rocks; none have yet been made of the andesitie types. 



Making use of the instructive variation tables given by Summers' 

 (33, Fig. 3, p. 270), it is seen that the important types of Devonian- 



N' 8. 



Brogger Diagrams 



Odcire , Brdcmar House , Maccdon. 



t^SKwrs ^nei Summers)? 



Grdiiodionre,BraemarHouse,M£]cedorr:5 



N»57. 



Fi-q3: 



6Tdmte, Gabo Isldrni 



(^Siimmers, 33.)' 



Fiq 4. 



Qudrrz-Porph\|nte,TcircS R<^nqe , 

 (^Spec.ioo. ,/\nrfl.,Thi£le) 



Fia 5. 



Rhyolire, WWellinoroM 



Quarlz-Cerarophjre , Mowj Nowa; 

 (Spe(.68.An<)I.Thitle) 



