BY W. N. BENSON. 593 



in Argyllshire, which was described by Dr. Fletti*!), a specimen 

 of Avliich was kindly given to the writer by Dr. H. H. Thomas (a 

 slice from specimen 13218 of the collection of the Geological Sur- 

 vey of Great Britain.) The preservation of the subvariolitic struc- 

 ture in the epidote is very distinct. 



The amphibole-schist, derived from the metamorphism of the 

 spilite, which occurs in Portion 155, Nemingha, is considerably 

 decomposed (1338). The original structure has been entirely lost, 

 and the large grains of plagioclase have been replaced by finely 

 granulated albite, while the remainder of the rock consists of 

 matted chlorite and actinolite, dotted with minute grains of titano- 

 morphite. Another form of altered spilite occurs in the north- 

 eastern corner of the area mapped in Portion 04, Nemingha(1323). 

 It has completely lost its original texture, and has now the habit 

 of a fine-grained amphibolite. It consists of a mosaic of interlock- 

 ing grahis of untwinned albite, actinolite scattered irregularly in 

 isolated prisms or sheaf-like aggregates, and a little irregularly 

 granular sphene, sometimes in small clusters. A few prisms of 

 apatite are also present. Slide 1305, from the same locality, is pro- 

 bably an altered vesicular magnetite-quartz-keratophyre-tuff. It 

 is a strongly schistose rock (see Plate Hi., fig. 1). The grey, dusty, 

 felspathic groundmass is too minutely granular for determination. 

 It is sprinkled with small isolated prisms of hornblende, and 

 well formed crystals of magnetite, evenly though not densely dis- 

 tributed throughout the rock. Interlaminated with the grey fels- 

 pathic portions, or forming fragments in it, or apparently filling 

 vesicles, is a mosaic of quartz-grains, with abundant prisms of 

 actinolite. The rock has been so cut by "schuppen" shearing, that 

 the form of these has been largely lost. They perhaps result from 

 the recrystallisation of interlaminated and fragmentally included 

 sedimentary material, and the in filtered infilling of vesicles. 



The vitreous rock from Pine Hill (1119) has been described 

 above (p. 547). It is more acid than most of the other rocks of 

 spilitic suite in the Eastern Series. 



