BULLETIN 
OF THE 
WISCONSIN NATURAL HISTORY SOCIETY 
Vol. 10 DECEMBER, 1912 No.. 3 and 4 
OBSERVATIONS OF THE BEHAVIOR OF 
BUBRANCHIPUS DAD AY I. 
By A. S. Pkarse. 
During the spring of 1912 (April 22 to May 10) the writer 
had opportunity to observe the hebavior of Bubranchipus dadayi 
Pearse in a small pool on the low ground along the Merimec River 
near St. Louis, Missouri. According to the farmer who owned the 
land, this pool had contained no water until the snow melted in 
the spring; and it became temporarily a part of the river during 
the high water period of April 28 and 29. Though the pool was 
rather large (330 x 55 ft.) and shaded to some extent by the trees 
and shrubs which grew in and around it, the water was shallow 
(2^2 feet) and; became warm during the day. For example, on 
April 27 the temperature just below the surface at 8.25 a. m. was 
12 0 C., at 17.07 p. m., 16.9° C., and at 2.35 p. m., 15.3 0 C. 
The movements of fairy-shrimps are extremely easy and grace¬ 
ful ; those of this species are no exception. While in locomotion 
the ventral side is usually uppermost and the body glides through 
the water slowly but steadily. Changes in direction are accom¬ 
plished by a quick “flirt” of the tail. In ordinary swimming, waves 
of movement appear to pass along the ventral side toward the pos¬ 
terior end—each appendage stroking a little oftener than twice per 
second—and the body moves through the water at the rate of about 
one foot in ten seconds. An animal swimming at the surface may 
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