REPORT OF COMMISSIONER OF FISH AND FISHERIES. LXY 
taken from them on nearly every trial made with the large oyster tongs, 
they seemed to have little, if any, effect in shielding the neighboring 
oyster beds. Moreover, this method is said to have been tested un- 
successfully off Bridgeport, Conn. Under favorable conditions the 
mussels also grow very rankly, tending to displace the oysters and ac- 
cumulating much mud about them as well as other unwholesome mat- 
ters. Baited traps placed on and about the oyster beds have likewise 
been tried by the oystermen and by the 3?ish Commission, but they 
have not proved generally effective, although a certain measure of suc- 
cess has been reported from their use in some localities. 
At New Haven a large map was prepared showing the location and 
extent of all the planted oyster beds in the harbor, and of the natural 
beds on the west side of the entrance. Density and temperature ob- 
servations were also taken as in Providence Biver, but not so closely 
together. 
Arrangements have been completed to begin upon the investigations 
in Long Island Sound during the summer of 1889, and they will sub- 
sequently be carried southward along the coast. Other inquiries per- 
taining to the Atlantic coast, conducted during the past year, are 
described under special headings. 
INVESTIGATION OF INTERIOR WATERS. 
The object of investigating the different lake and river systems of 
this country upon a broad and comprehensive basis has been explained 
in the preliminary remarks, but while the importance of such inquiries 
has all along been recognized, the subject received comparatively little 
attention from the Fish Commission until the present year, when it 
was taken up as an essential feature of the scientific work. The prob- 
lems involved here, as in other branches of the field work, are of two 
classes, physical and biological, the latter being again divisible in con- 
formity with popular classification, according to whether they relate 
to fishes, invertebrates, or plants. 
The collection and study of the fishes may proceed with considerable 
rapidity, owing to their relatively large size and the convenient means 
devised for their capture both by naturalists and fishermen, but the 
physical questions, and more especially the aquatic invertebrates, rep- 
resented by a countless number of varieties and composed in large part 
of almost microscopic forms, present far greater difficulties in the way 
of detailed observations, and will require a much greater length of 
time to secure appreciable results. Owing to the different nature of 
the field work called for by each of these branches, they must to a 
great extent be taken up and carried along independently of one 
another. No other method is generally expedient unless it is desired, 
by means of a reconnaissance, to obtain immediate information respect- 
ing the combined features of any particular region. A party, specially 
H. Mis. 274 v 
