47 
the Reservoir Extension. It is composed of phenocrysts 
of deep brown hornblende, with iron ore and a small 
amount of accessory pyroxene and olivine, in an isotropic 
groundmass which also holds some small laths of plagio- 
clase and a little nepheline. The second (No. VIII) is 
from a dyke which occurs at the Mile End quarries, 
but which is now concealed by a recently constructed 
road. 
Fourchite. This is an olivine-free augite hornblende 
monchiquite which is represented by a few dykes. See 
St. Helen’s Island, p. 59. 
Camptonite. The camptonites are dark in colour, 
fine in grain, holocrystalline and often porphyritic. 
They frequently show a more or less banded stiucture 
parallel to the walls, and, like the monchiquites, are 
occasionally amygdaloidal, the cavities being filled with 
zeolites or rhombohedral carbonates. They usually belong 
- to the subdivision of the hornblende camptonites, the rock 
being composed of hornblende (deep brown), pyroxene 
and plagioclase as essential constituents with accessory 
nepheline, perowskite, apatite, iron ore, &c. 
Analyses of three of these dykes are given on page 
46. The first two (Nos. IX and X) occur at the Reser- 
voir Extension and were analysed by Dr. B. J. Harrington. 
The third (No. XI) is an exceptionally fresh camptonite 
from Mount Royal recently analysed by M. F. Connor. 
Alnoite. These olivine-rich biotite monchiquites, 
holding melilite and perovskite, are excellently represented 
in this area. It is one of the few places in the world where 
these rocks are found. Unfortunately it is impossible for 
the members of this excursion to see the rock in place, 
since the localities where it occurs are difficult of access, 
or the dykes at one time laid bare are now covered by the 
waters of the St. Lawrence or Ottawa rivers. The first 
locality in which alnoite was found was in a dyke cutting 
the Potsdam sandstone in the bed of the Ottawa river at 
Ste. Anne-de-Bellevue at the west end of the Island of 
Montreal, where it was laid bare many years ago in a 
cofferdam put down for the purpose of blasting away an 
obstruction in the rive: bed. It occurs as a dyke rather 
over two feet (-6 m.) wide, the rock presenting a very 
striking appearance owing to the presence of large rounded 
