158 BULLETIN: MUSEUM OF COMPARATIVE ZOÖLOGY. 
to epidote and chlorite. The igneous tongues partly enfold the pebbles 
and finally become dissipated among the interstices of the conglom- 
erate. The data plainly show that the melaphyr, in these localities 
at least, is intrusive. 
Sandstone and Slate:—Composition. The sandstones of the Rox- 
bury series contain besides quartz a considerable proportion of fel- 
site and feldspar. Of twenty-seven specimens examined seven con- 
tained felsite and four contained feldspar. The cement is usually 
silicious and the rock is firm and dense. The slates are sometimes 
sandy but they are generally argillaceous and compact. 
——:—Texture. The sandstones are sometimes coarse grits with 
fragments ranging up to a quarter of an inch in diameter. Ordinarily, 
however, they are finer textured though their grains are often not well 
sorted. The fragments of which they are composed are seldom 
rounded but usually angular or subangular. 
——:—Color. The colors of both the sandstones and slates are 
prevailingly gray, though other colors are represented singly or in com- 
bination. Of the twenty-seven specimens of sandstone examined seven- 
teen (63 per cent) had gray tones, while in the case of the slate the 
percentage was-not quite so high (thirteen out of twenty-two specimens 
or 59 per cent). In the case of the sandstones green and purple tints 
rank next in frequency of occurrence, the green appearing in 5 per cent 
of the specimens examined and the purple in 48 per cent. In the case 
of the slates, however, purple colors are more common than green, 
the percentages of occurrences in the twenty-two specimens examined 
being forty-five and twenty-seven respectively. Drab and red tints 
occur less frequently in both sandstones and slates but they are of 
relatively slight importance. If ‘the reds are classed with the purples 
the enumeration of percentages for the slates will scarcely be affected 
but in the case of the sandstones the figures for purple and green 
colors will stand fifty-six to fifty-one in favor of the purple instead of 
forty-eight to fifty-one in favor of the green. ‘Thus in the finer sedi- 
ments the prevailing color is gray but purple and reddish tones are 
next in frequency and almost as abundant as the gray. Here again 
these colors are not confined to any particular locality but are on the 
whole widely distributed. 
:—Bedding. The evidence as to characteristics of bedding 
gathered from the hand specimens is unsatisfactory. Of fifty specimens 
examined only eight give any information bearing on this topic. A 
specimen of slate from Newtonville shows fine, even bedding and a dark 
gray slate from Quincy (Boston IX, V 32, Plate 7) is uniformly banded 
