210 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
barrier to the entrance of the salt bottom water from the centre of 
the Gulf. And Jeffrey’s Ledge evidently acts in the same way, for 
though it leaves an open entrance on the north to the trough west of it, 
the fact that the salinity was the same at eighty fathoms in the trough 
as at forty fathoms east of the Ledge, shows that little if any salt water 
flows in across the latter. 
In the profile (Fig. 50) from the mouth of Penobscot Bay (Station 
10102) to the centre of the Gulf (Station 10090) via Jeffrey’s Bank 
Fa.o 33 100 92 | 
Fia. 51.— Salinity profile from the neighborhood of Mt. Desert Island (Sta- 
tion 10099) to the eastern basin of the Gulf of Maine (Stations 10100, 
10092). 
(Station 10091), the salinity curves all dip shoreward between the | 
surface and forty fathoms. This is true for the whole column of water _ 
between Jeffrey’s Bank (Station 10091) and the mouth of the Bay | 
Station 10102). But between Station 10090 and the Bank, the re- — 
verse is the case below forty fathoms. The curve of 33.2%p is espe-_ 
