142 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [436] 
II. 9.—FREE:-SWIMMING AND SURFACE ANIMALS. 
Under this head I have included all the animals found swimming free, 
whether in the bays and sounds, or in the colder region outside. Nor 
have IJ, in this case, attempted to separate those of the estuaries and 
other brackish waters, although such a distinction might be useful had 
we sufficient data to make it even tolerably complete. But hitherto 
very little surface-collecting has been done in waters that are really 
brackish ; and, moreover, since every tide must bring in myriads of free- 
swimming creatures with the waters from outside, it will always be diffi- 
cult to distinguish between those that are thus transported and. those 
that properly belong to the brackish waters. A distinction between the 
free-swimming animals of the bays or sounds and those of the open 
coast has not been made, partly on account of the constant intermixture 
of the waters and their inhabitants by the tides, and partly because the 
observations that were made do not indicate any marked difference in 
the life or in the average temperature of the surface waters, though the 
waters of the shallow bays become more highly heated by the direct 
heat of the sun in summer. The waters of the open coast are evidently 
more or less warmed by the Gulf Stream, and in fact numerous species 
of animals that properly belong to the fauna of the Gulf Stream are 
constantly brought into Vineyard and Nantucket Sounds by the eur- 
rents, showing conclusively that a portion of the Gulf Stream water 
must also take the same course. 
In Vineyard Sound, during August and the first part of September, 
the temperature of the surface water in the middle of the day was gen- 
erally from 68° to 71° Fahrenheit; September 9, off Tarpaulin Cove, 
the surface temperature was 66°; off to the west of Gay Head, in mid- 
channel, it was 67° Fahrenheit; but farther ont, off No Man’s Land, on 
the same day, it was 62°, (bottom, in 18 fathoms, 624°;) a short distance 
west of No Man’s Land it was 63°, (bottom, in 11 fathoms, 59°;) about 
sixteen miles off Newport, at the 29-fathom locality, it was 62° on Sep- 
tember 14, (at the bottom 59°;) off Cuttyhunk, in 25 fathoms, it was 
64° at the surface on September 13, (bottom 624°.) According to the 
record made by Captain B. J. Edwards, during the past winter, from 
observations taken at 9 a. m. every morning, at the end of the Govern- 
ment wharf at Wood’s Hole, (where the temperature must be nearly 
identical with that of Vineyard Sound,) the average temperature of the 
surface water was 31° Fahrenheit, from December 27 to February 28. 
The average temperature for that hour during January was 31.42°; 
the lowest was 29° on January 29, with the wind N. W.; the highest 
was 38° on January 17, with the wind 8. W.; on the 18th, 19th, and 
22d it was 35°, The average for February was 30.75°; the coldest was 
29°, on February 24 and 25; the highest 33°, on February 8, 17, and 
19. The temperature at the bottom (at the depth of nine feet) was 
also taken, but rarely differed more than one degree from that of the 
