ON THE DEPENDENT ISLES OF TAIWAN. 39 



kind of VigJit-hrownish colour, and its plates are often multiple- 

 twinned, and enclose, besides plagioclase, a number of round and 

 corroded crystals of olivine which is for the most part changed 

 into green, pleochroic fibres ; the iddiugsitization of the olivine was 

 so far not observed. The 2)loffioclases are of two generations (i^/y. 2), 

 the larger, probably intratelluric, species has fissures (?ee Fig. 2) 

 filled with films of brown hydrous sesquixide of iron, which 

 cause the phenocrystic feldspar to appear 'niacroscopicalli/ like an 

 olivine. The plagioclase is partially embraced by the ophitic 

 plate, while the smaller laths became entirely enclosed in it. 

 The polygonal inters{)ace3, when not occupied by augite, are 

 otherwise filled up wâth the fibrous devitrified glass, the latter 

 containing globulites, sometimes dendritic, and apatite ; and the 

 thick lamellœ of ilmenite traverse the base, but not the plate of 

 augite, consequently the crystallisation of the ore must have 

 taken place posterior to that of the pyroxene. Sometimes the 

 greenish-yellow augite is coarse-granular, and in this case the 

 structure approaches to that of inlersertal. Ilaynetile seems to 

 be ^vanting. Owing to the coarseness of the structure, the rocks 

 are often porous, and the polygonal, angular spaces are often 

 filled up with banded, purplish chalcedony. 



I). THE TYPE OF THE LI VINE-LESS BASALTS. 

 {PL I, Fig. .3 ; PI. II, Fig.^. 2 and 3.) 



The olivine-less, hypersthene-bearing Basalts are represent- 

 ed in my collection by two specimens from ^Yampai", and one 

 from each of the following islands, Hoko^', Kin-sho'^', and 

 Hatto-sho^'. They are megascopically wet-grey, and fine-granular, 



1) WM 2) Sei-kei ®^ in Hôko 3) ^g| 4) A^^. 



