Benton.] - 494 [February 18, 
the resulting supposition that parts of the amygdaloid are essentially 
the same as the pudding-stone. 
The features in question have already been described in this paper 
(page 421) under the head of spheroidal and angular inclusions. 
The objections to Prof. Shaler’s conclusions are. First: —That 
the forms in question do not in any sense represent the pebbles of the 
pudding-stone. Second:— That no part of the amygdaloid forma- 
tion is essentially the same as the Roxbury pudding-stone. 
It may be said as a minor consideration that, whereas the pudding- 
stone is wholly made up of rounded fragments, on the other hand, 
large numbers of the inclusions of the amygdaloid are angular. 
The two masses of rocks which have been cited as offering proof 
of the transition, are so different in their nature, that they must be 
treated of separately. That near the small cemetery on Warren Street 
is neither the amygdaloid nor the conglomerate. It is a fragmental 
rock made up chiefly of the debris of melaphyr rocks. This is shown 
by microscopic examination. A few of the constituent particles are 
quartzose or feldspathic, and'there are a very few very small pebbles 
of quartzite or felsite scattered through the rock. Nothing can be 
proved from such a rock, since it is entirely different from both of 
those which are under consideration. 
With regard to the other rock cited, 7.e., that at the corner of 
Harvard Avenue and North Beacon Street, even if it be granted that 
so far as the contours of the inclusions in question are concerned, 
this rock resembles the pudding-stone, it is impossible to consider 
them as the pebbles of that rock without entirely disregarding their 
lithological character, for every one of these bodies in the amygdaloid 
is now composed of the same kind of rock as that in which they are 
included, that is to say of melaphyr, an alteration product of basalt. 
This may be seen not only in the field, but in hand-specimens, and 
especially under the microscope. 
The conglomerate is, as regards its constituents, an extremely 
heterogeneous rock. It contains pebbles of quartzite, felsite, 
eranite and gneissic pebbles; also pebbles of syenite and clayslate. 
It appears to be Prof. Shaler’s supposition that, by the process of 
fusing, these lithologically different pebbles were all transformed into 
one and the same kind of rock, namely into melaphyre, or rather 
basalt, since what is now a melaphyre was, at the time it con- 
solidated, a basalt. : 
Now, it is clear that the Roxbury conglomerate is a highly 
