Si aie 
MUSEUM OF COMPARATIVE ZOOLOGY. 127 
sistent contrast between the features of the upper contact in the western 
and eastern sheets. These need not be again stated ; suffice it to say 
that the features of the western sheet demonstrate the trap to be sec- 
ondary to the sandstone, while those of the eastern sheet are equally 
conclusive in showing the sandstone to be secondary to the trap. It 
does not seem too much to say that all the many peculiar features of 
these two sheets find reasonable explanation as consequences of the 
strongly different conditions of their origin. 
The localities referred to above as yielding trap fragments, but not , 
lying on the back of a trap sheet, are the trap conglomerate of the 
. anterior to Lamentation Mountain, which is certainly the stratigraphic 
equivalent of the adjacent trap sheet ; the heavy trap conglomerates 
northeast of the first posterior ridge to Saltonstall Mountain, which are 
perhaps to be associated with the posterior, although probably dislo- 
cated from it by faults ; and a single case sonth of Durham, where one 
fragment of vesicular trap was found in a conglomerate, distant from 
any trap sheet, but near the eastern crystalline boundary of the for- 
mation. 
Meriden Quarry. Locality 19 (Figs. 5, 18).— The Meriden City 
quarry, in the easternmost ridge of the Hanging Hills group, has been 
attentively studied, and with much profit. Suites of specimens were 
carefully collected from above and below the surface of separation be- 
tween the upper and lower masses of trap which appear here, with a 
view to examining the evidence of double flow presented. Numerous 
specimens were also taken from the linear breccias of sandstone and 
trap fragments which traverse the quarry, in order to compare them 
with fragments of sandstone included in trap, such as occur in a dike 
at Mount Carmel, locality 27, several miles to the southwest, and to 
discover if they should in any way bear on the intrusive or extrusive 
origin of the Meriden sheet. 
The lower mass of trap, a, a, Fig. 18, is seen beneath the upper, 3, 3, 3, 
on the west side of the quarry, where abundant evidence may be found 
to show that the two were produced by separate eruptions. They are 
divided by a somewhat irregular surface, like that of rolling ropy lava, 
and usually marked by a seam, more or less open to the weather. The 
lower trap is changed to a reddish brown color for a depth of three feet 
or more below its upper surface, and contains numerous amygdular areas 
of chlorite, giving it a mottled appearance, simulating an altered sand- 
stone to the eye. The reddish brown color gradually disappears down- 
