62 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
than Stations 45 and 46, made almost simultaneously, shows that the 
discrepancy below seven fathoms between it, and Stations 2 and 7, 
can not be wholly the result of seasonal change, in the sense of solar 
warming. Hence it seems safe to say that at Station 43 we encoun- 
tered a water mass distinctly warmer than the waters west, north, or 
northeast of it. But of course it is impossible to know whether this 
warm water would have been encountered off Cape Cod earlier in the 
season, or whether it had moved thither between the times of our 
two visits to Massachusetts Bay. 
SALINITY. 
As pointed out above, titration is, on the whole, the most satis- 
factory method for determining salinity, (the term salinity meaning 
the number of grams of solids per kilogram of water); and the follow- 
ing account of the salinities of the Gulf of Maine is based entirely on 
the values arrived at by this method. 
Every water sample was titrated twice, some of them three or four 
times, and to test the possibility that some evaporation or other 
alteration in the salinity of the samples might have taken place be- 
tween collection and titration, the titrations for four samples, chosen 
at random, were repeated after an interval of two months, with the 
following results :— 
Station Trial A Trial B 
27, surface 32.66 32.66 
43 95 fathoms 33.69 eb ae 
22 45 r 32.74 BS 
2 60 a 32 .92 32.91 
The pairs of salinities agree so closely that there was evidently no 
appreciable change as a result of storage. 
Surface salinity— The chart of surface conditions in July and Au- 
gust, 1912 (Plate 2) shows that the salinity was lowest close to the 
coast, there being a band five to twenty miles broad reaching from 
Cape Ann northward nearly to Cape Elizabeth where the salinity 
was below 31.4, while it was highest along the western edge of the 
Gulf, over the Nova Scotia Coastal Bank (Station 31), where water 
of 32.84 was encountered. The curves clearly show two distinet 
masses of water of low salinity intruding into the comparatively salt 
waters of the central part of the Gulf. One of these was off Cape Ann, 
where the curves of 31.4, 31.8 and 32, swing far to the eastward. The 
