188 ].] 
169 
[Kingsley. 
3. The felsites are truly eruptive rocks more recent than the 
granites. There were at least two eruptions of felsite in each 
area, and in the southern area there were probably three. 
4. The fragmental material so intimately associated with the 
felsites upon Brekheart Hill is a volcanic ash ; elsewhere the 
fragmental rocks have generally been derived from material 
eroded and deposited by water. 
5. The very porphyritic, pebble-bearing felsite between Long 
Pond and Prospect Hill, part of the W akefield and Cliftondale 
felsites, and probably the dark-colored felsites of Malden High- 
lands, are younger than the tufas and conglomerates with which 
they are associated. 
6. The diorites are eruptive and younger than the felsites. 
7. The diabases and melaphyres are the youngest eruptive 
rocks of the region, and there has been in the order of eruption 
beginning with the granites, a general progress from siliceous to 
basic rocks. 
The following paper was read : 
A CASE OF POLYMELY IN THE BATRACHIA. 
BY J. S. KINGSLEY. 
Isidore Geoffroy St. Hilaire in the third volume of his classic 
work on Monstrosities ( 12 , p. 262) applies the term Polymely 
(Polymelie) to those abnormal forms where one or more extra 
limbs are developed. Cases of supernumerary limbs are ex- 
tremely rare in the Batracliia, or, at least, but very few have been 
described, and then but very superficially. Mr. Dumeril states 
( 4 p. 912) that three or four thousand frogs are required annu- 
ally to feed the animals in the menageries of the Museum of 
Natural History in Paris and that out of the large numbers which 
he has seen brought for this purpose not a single example of 
supernumerary limb had been found. 
So far as I am aware the following list embraces the entire 
literature of the subject. Passing by the older papers of Super" 
ville, 13 Guettard, 7 Otto 10 and Van Dcen 3 quoted by Dumeril, 4 which 
give no anatomical details, our first reference in modern times is 
