90 B. KOTO. 



colour, and they are called respectively " brown or green slate." Both 

 varieties come together in the same geological horizon, insensibly 

 merging into one another. They decidedly belong to the paleozoic age, 

 and are overlaid by the s«5-carboniferons (?) limestone* which is ex- 

 tensively developed in Japanf and China.| The writer has often 

 observed in fields, even, interstratification of tlie diabase-tuff with the 

 subcarbonifdrous limestone. 



It is slaty in its outer appearance, but less fissil than common 

 roofing slates, and is so named "slate " by geologists of the geological 

 survey of Japan. This diabase-tuff becomes not unfrequently massive 

 and at the same time porous, being filled with calcite; thus it has then, 

 all the appearances of melaphyre. 



The lamellar-granular ( ' flaserige ' ) rock-mass encloses the round, 

 bent augite, and produces a structure similar to that seen on a large 

 scale in the " augen-Gneiss." The typical specimen comes from Ana- 

 nai, in Tosa province, near the Kunimi-yama. 



The aiigite which the writer supposes to be diallage, but without 

 being able to give a decisive proof, presents quite a fresh vitreous 

 aspect, although traversed by irregular transversal fissures in various 

 imaginable directions. The augite shows neither the tendency of a 

 parting in the orthopinacoidal direction, nor that characteristic inter- 

 position very common in the gabbro-diallage. In sliort, it is just like 

 augite in younger eruptive rocks ; the mineral is olive-green or brown 

 in colour. 



The augite is weakly pleochroic on the clinopinacoid, while on 

 the orthopinacoid pleochroism is scarcely discernible. The extinction- 

 direction varies from 23" — 31° with the trace of cleavage parallel to 

 C. The writer does not wish to lay much stress on the angular 



* Cf. C. Güttsclie, ' Science; Vol. I, p. 10(5. 



t E, Naumann, 'Ueber den Bau uud die Eutstehnug der japanischen Inseln.' 



I V. Eicbthofen, 'China.' 



