200 TRANSACTIONS OF THE [APR. 15, 
in the deeply stained outside a minute pilitic structure is re- 
tained, apparently of feldspar rods arranged approximately par- 
allel to the flow lines. If the apparent remains of radial_struc- 
ture are not illusory, this would seem to indicate either : 
1. That a radial spherulitic structure could form in a rock 
already in large part crystallized, or 
2. That this pilitic structure of the groundmass may be of 
secondary origin. 
Of these two, the former supposition seems to the writer the 
more probable one. 
The Survey Reports mention in general terms,* and in one 
case more particularly, gradations of these felsites into the 
holocrystalline rocks with which they are in places associated. 
Dr. Ells speaks of these holocry stallines as basal portions of 
voleanic flows; Dr. Bailey} considers that north of the Germaine 
Brook as an extreme case of metamorphism. The present 
writer has not yet been able to obtain a complete series show- 
ing this gradation, though a partial one was made at Germaine 
Brook. But in none of the felsites sectioned is there evidence 
of gradation into crystalline rocks, either by slower cooling or 
subsequent metamorphism. That such deeper-seated facies of 
the Huronian igneous rocks exist there can be no doubt, and it 
would probably be revealed by more extended study. 
The acid breccias and ash-rocks are very abundant. Coarse 
felsite breccias occur east of Coldbrook, where they contain 
larger rounded or pear-shaped masses, probably volcanic bombs; 
on the road skirting the south flank of Bloomsbury Mountain, 
here composed of a pale greenish-gray silicified felsite, strongly 
flow-lined and perhaps a devitrified glass; at Titus’ Mill on the 
Hammond River, here being partly a devitrified glass breccia ; 
in a railway cutting near Henry Lake, and elsewhere. The finer 
breccias or coarse ash-rocks are sometimes schistose, as for 
instance, a greenish-gray breccia not far east of Coldbrook. 
With increasing fineness they are more and more altered and 
less easy to recognize, the fine-grained, flinty felsites and petro- 
silex showing no characteristic structures which can be consid- 
ered original. 
These fine- grained rocks often show aggregations of chloritic 
material in rounded or irregular spots with fairly well defined 
outline. Aside from this they are uniformly micro-crystalline 
in structure, made up of feldspar with a quarter or less admix- 
ture of quartz, and scattered magnetite grains. Occasional large 
grains and porphyritic crystals of feldspar are seen in some 
specimens. 
* E lls, 187 7-8. 
+ Bailey, 1877-8. Discussed in this paper under soda granite. 
