536 EOZOON CANADENSE. 
they are parts of original strata included in the gneiss; but their 
position may also be explained in accordance with another theory, 
in support of which. I shall offer some evidence. 
2. The principal deposits occur along the line of an anticlinal, 
filling cavities produced by the folding and the falling, down of por- 
tions of the included strata of the gneiss. The anticlinal position 
is most clearly shown at Chelmsford, where there are four veins 
or. masses of the limestone, in two lines coinciding with the strike 
of the gneiss. 
These lines are about half a mile apart; extending in a north- 
east and southwest direction ; the strike, as observed by the com- 
pass, being north 65° east. The strata of the gneiss dip in 
opposite directions from these lines; toward the northwest at an 
angle of about 65°, to the southeast at an angle varying from about 
70° to a nearly vertical position. 
The deposits are all of very limited extent, the largest being 
at the surface not more than two hundred and twenty feet in 
length, and about sixty feet in width, including the intervening 
bands of gneiss. 
The aggregate length of all the limestone deposits that occur 
along a line of some twenty-five miles in length, is probably less 
than one thousand feet. 
The vein-like character of the limestone is most plainly shown 
in one of the abandoned quarries in Chelmsford. The deposits | 
here occur in two principal veins extending in the direction of the 
strike of the strata to about two hundred feet in length. The 
structure here plainly shows that cavities which ‘have become 
filled with the limestone were formed by the folding and faulting 
of the strata of gneiss. The masses of limestone are separated 
by strata of gneiss which are also folded and arched over, en- 
closing cavities filled with the limestone. : 
At one of the quarries it can be seen that the limestone rested 
against the irregularly fractured ends of strata of gneiss, which 
fill a small space in one of the excavations, completely dividing 
the limestone into two masses. 
That the limestone was deposited in cavities mostly closed at 
the top, which have since been uncovered and exposed at the sur- 
face by the denuding action of the drift, seems to me a reasonable 
deduction from the facts observed. 
It is worthy of note that the gneiss of the enclosing walls of 
