KECENT PUBLICATIONS 379 
quartz inclusions. ‘The grains of augite sometimes show the effects of 
mechanical movements in the fracturing of grains which lie in contact 
with the granular bands. 
In the ellipsoidal rock the granular bands are more pronounced 
and strongly marked by the presence of pyroxene. Quartz appears 
in greater amount than in the coarsed-grained rock. In the streaked 
gneiss all the constituents are finer grained. Hornblende appears 
here frequently, sometimes in sharply idiomorphic crystals. Both in 
their field relation and in their microscopical structure these rocks 
show a gradation from the coarsely crystallized rock to the fine- 
grained streaked gneiss. 
In the classification of gneisses it is suggested that the term gneiss 
be used in the broader structural sense following the prevailing usage 
among Canadian geologists; where the origin of the rock is known a 
corresponding qualifying term may be used as diorite-gneiss. Where 
the origin is unknown, the ending “‘ic”” may be given to the qualifying 
term to show its structural relations, as dioritic-gneiss. In harmony 
with this view the rock under consideration would be a pyroxene- 
syenite-gneiss. As to the origin of the ellipsoidal structure the evi- 
dence, while in many respects incomplete, involving as it does much 
that is as yet little understood in the metamorphism of rocks, seems 
on the whole to favor the hypothesis of dynamic metamorphism. 
Briefly summarized this supposes: 
1. That the structure characterizing the Leopard rock is due to 
orographic agencies and represents an intermediate stage in the 
development of a streaked augite-syenite-gneiss out of an augite- 
syenite, which was distinguished by a coarsely crystallized structure 
and by a somewhat irregular aggregation of pyroxene. 
2. That the distribution of the pyroxene has been effected by the 
solution of portions of the original constituents and their recrystal- 
lization along lines marking the location of the cracks. 
3. That with continued pressure these lumps have been more and 
more drawn out, the process being accompanied by recrystallization 
until the rock assumed the streaked gneissoid form. 
RECENT PUBLICATIONS. 
—ADAMS, FRANK D. and B. J. HARRINGTON, On a New Alkali Hornblende and a 
Titaniferous Andradite from the Nepheline Syenite of Dungannon, Hastings 
Co., Ontario, 9 pp.—Am. Jour. of Science, Vol. I, 1896. 
