PLATE XXXVII. 



FIG 1. 

 HOENBLENDE- ANDE SITE . 



TOP OF BEINN NEVIS. 



Magnified 50 diameters. Ordinary light. 



The porphyritic constituents are plagioclase (10), and hornblende (8). 



The large plagioclase crystal is completely honeycombed with inclusions. 

 The hornblende is idiomo r phic. The section of the small individual to the right 

 of the group is bounded by the forms (110) and (010). The groundmass is 

 composed of felspar microlites, specks of iron-oxide, glass and indefinite double 

 refracting matter. The rock is probably of Upper Palaeozoic age. 



FIG. 2. 

 ENSTATITE-POEPHYEITE. 



HALF-A-MILE ABOVE SHILLMOOR ; CHEVIOT DISTRICT. 



Magnified 25 diameters. Ordinary light. 



The porphyritic constituents are labradorite (10), and enstatite (2). The 

 latter mineral is now represented by fibrous pseudomorphs (? bastite) which 

 sometimes polarize as aggregates and sometimes as individuals. 



The groundmass is a glass crowded with felspar microlites and magnetite 

 granules. The labradorite crystals contain irregular inclusions of the 

 groundmass. 



