194° BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
tion with the occurrences of an elevated sea-floor already described by 
Stone and others on the coast of Maine where marine fossils have been 
found above the latest glacial drift, makes it difficult, it seems to me, to - 
escape the conclusion that marine action rather than glacial lake waters 
was also concerned at Cape Ann in the making of the beaclies described 
by Professor Tarr and myself. In a paper uow in preparation, I purpose 
to show that in the southern part of Massachusetts the last ice-sheet 
existed longer, along and off the coast, than it did on the mainland west 
of Cape Cod bay, thus allowing the formation and temporary existence 
of what may be termed proglacial lakes, or bodies of fresh-water, held in 
front of the ice by a glacier-dam crossing the mouths of valleys, already 
freed from ice ; such a body of water as Professor Crosby has claimed, 
may have existed in Boston harbor, and even northward along the coast. 
The fetch of the waves from the northeast necessary to produce the long 
shore drift observed at Whale Cove on Cape Ann, however, is quite 
beyond the possibilities of any contemporaneous glacial lake which the 
facts discovered in the Cape Cod district would warrant. 
