STJBROTTNDING THE LAND's-END MASS OF GRA^TE. 427 



Fig. 6. Altered mica-schist containing radiating crystals of tremolite and bands 

 of magnetite. See p. 410. Magnified 20 times. 



Fig. 7. Transverse section of polygonal prism of tourmaline composed of alter- 

 nate bands of blue and brown colour. See p. 415. Magnified 

 60 times. 



Figs. 8, 9, & 10. Small crystals of tourmaline with one end regularly terminated, 

 the other formed of slender prisms. See p. 416. 



Fig. 11. Gneiss {altered Silurian slate) in contact with granite, consisting of 

 orthoclase, quartz, and mica, Ballynamuddagh, co. Wexford. See 

 p. 411. Magnified 10 times. 



Fig. 12. Contorted mica-schist {altered Silurian slate), co. Wexford. See 

 p. 411. The rock has been bent into numerous sharp contortions, 

 and compressed in the direction of the pressure to about two thirds 

 its original dimensions. 



All the figures, with the exception of fig. 1 , have been carefully drawn under 

 the microscope by the author, with the aid of the camera lucida. 



