22 TIE JOURNAL OF GEOLOGY: 
errors will not affect the general conclusion that may be drawn 
from the observations. 
The sub-classification of these two main groups allows of more 
latitude, but is readily done by means of the ferro-magnesian 
silicates, the writer preferring this to a classification based on 
structure such as Rosenbusch adopts for the dacites.* It must 
be borne in mind that between some of the groups gradations 
occur, though on the whole there is less difficulty from this 
source in the present district than in many others. In the final 
classification then I have followed in the main that of Kuch? 
for the closely similar Colombian eruptives, though my scheme 
differs from his in distinguishing between the augite and the 
hypersthene-andesites. 
I divide then the dacites into: Hornblende-Dacite ; Hornblende- 
Hypersthene-Dacite, and brotite-Dacite. 
The andesites are divided into: Hornblende-Andesite; Biotite- 
Flornblende- Andesite; Hornblende- Augite- Andesite;  Hypersthene- 
Andesite, and Hornblende-Hypersthene-Andesite. 
It may seem unwise to give a mixed, and from a certain point 
of view a subordinate, group like the last as much prominence as 
a chief group such as the hornblende-andesite; but, leaving other 
considerations aside, it must be remembered that the present 
classification is merely for purposes of description in this paper, 
and not intended for general use. It has the further advantage, 
in the present case, of making the petrographical groups cor- 
respond, to a large extent, with their geological and geographical 
divisions. 
Hornblende-Andesite.—Rocks belonging to this group compose 
the whole of the Stavro district, z. e., Mts. Stavro, Paizochora, 
and Spasmeno Vouno, and are found as well along the north 
slope of Mt. Chondos, or Mt. Dendros, and at a small hill south 
of Kakoperato. While these various occurrences greatly resem- 
ble each other fundamentally yet there are certain small differ- 
* ROSENBUSCH, Mikr. Phys. II., 1887, p. 638. 
2 REISS and STUBEL, Reisen in Siid Amerika. Geol. Stud. i. d. Rep. Colombia, I., 
Petrographie. 1. Die Vulkanische Gesteine von R. Kiich, Berlin, 1892, pp. 18 and 19. 
