PLATE II L 



The Plate III illustrates the type-rocks from the Isles of 

 Koto (Botel-Tobago), and Kasho (Samasaua). 



Fig. 1. — Apo 01" altered andésite, magnified O-j diameters, 

 shoAving a pheuoerystie hornblende, with opacité margin (on the 

 right side of the figure). The hornblende is entirely decomposed 

 into an aggregate of pistacite, chlorite, and calcite-films. l^lagio- 

 clase is much decomposed. A dark spot (in the lower left octant) 

 is the iron-pyrite (p. '"i^). 



Fig. 2. — The same slide under crossed niçois. 



Fig. o. — A porous, greyish-l)rown basalt, Avith a rather large 

 corroded olivine (on the left of the figure). The ground-mass, 

 which encloses a corroded diopside-like augite, is highly fels- 

 pathic. The structure is hypocrystalline-porphyritic, approaching 

 to the pilotaxitic type (p. 48). 



Fig. 4. — Another basalt, with abundant olivine of various 

 dimensions. It contains globulitically granulated mesostasis, and 

 the structure is navitic (p. -30 ). 



Fig. '). — Hornblende-andesite, with dark hornblende-crystals, 

 surrounded by opacitic margin (on the upper and the lower end 

 of the figure). The structure is orthophyric (p. '30). 



Figs. l-'3 are all from the rocks of Koto. 



Fig. (). — Hypersthene-hornblende-andesite from the Isle of 

 Kasho, with a large ]jlienocryst of hornblende (on the right 

 half of the figure). It is enclosed by a thick margin of opacité, 

 but enclosing the grains of plagioclase after the fashion of 

 poikilitic plate (p. 55). 



