70 The American geologist. August - ' 
lie concordant with the true dip of the slates alongside. In some 
cases the surfaces of single pillow-, weathered out from their 
calcite matrix, were seen to have the exact appearance of ropy 
lava. 
A microscopic feature that especially distinguishes this pillow- 
lava is found in the appearance of two distinct kinds of mater- 
ial, which, in addition to the amygdule fillings, composes each 
of the pillows. In most of the small ones the chief constituent 
is a dark, brownish-gray or greenish-gray, aphanitic, basaltic- 
looking rock substance continuous from center to circumfer- 
ence. Within it, numerous round, light-gray to light greenish- 
grav bodies from 2 to 15 millimeters in diameter, lie embedded. 
(Plate XV, Fig. 3.) These bodies are less rapidly destroyed 
by the weather than their matrix and hence usually project so 
as to give the rock a "pimply" appearance. There is always 
a sharp line of demarkation between the two kinds of material, 
indicating that the differentiation of the two dated from the 
time of original solidification. The lighter-colored included 
bodies are, in fact, believed to be varioles, though it will be 
seen that, in their present highly altered condition, some of 
the characteristics of true varioles are absent. There is a 
marked increase in the size and abundance of the varioles with 
increasing distance from the periphery of the pillow. In that 
phenomenon is to be traced a connection with the yet more 
abundant pillows in which the core of each is occupied by a 
continuous mass of the variole substance. (Plate XIV, Fig. 2.) 
This common feature of the Xewfoundland rock does not seem 
to belong to the well-known variolitic pillow-basalt of Mont 
Genevre, although, in other respects, there is a close resemb- 
lance between the two lavas. All transitions may be seen from 
the pillows of the first class to those where the variole sub- 
stance composes as much as one-half to three-quarters of each 
pillow. The latter proportions adhere more especially to the large 
pillows. In no case was the variole substance apparent at the 
surfac.e of the pillow. As at Mont Genevre the varioles are 
generally arranged in concentric strings roughly parallel to the 
pillow-periphery. Near the light-gray core the varioles often an- 
astomose and may form branching vermiform projections from 
the core into the dark-colored crust. While the isolated var- 
ioles are commonly spherical or nearly so. it was observed in 
