156 CALIFORNIA FISH AND GAME. 
before hatching, nearly the whole body was covered with about eight or 
nine pairs of black bands. At the time of hatching this distinet band 
effect was somewhat destroyed by the round black spots seattered on 
the bands. 
The fish showed extreme activity at first, wriggling constantly and 
rhythmically, so that the taking of measurements was quite difficult. 
The most persistent motion was the back and forth movement of the 
tail, but occasionally the fish would curl itself into a tight knot and 
sometimes exhibit such violent activity, wriggling, squirming and flop- 
ping about, that it seemed lkely to wrench itself loose from the yolk. 
Such violent activity usually lasted only a few seconds. Most of the 
time the movements of the tail back and forth were quite regular, while 
at other times they were very irregular and jerky. These were counted 
at various times and under various conditions. They seemed to be 
fewer and more regular in the shade than in sunlight. The experi- 
ments were as follows: when the fish was put in a shallow pan and 
placed in the shade, the tail moved very regularly back and forth from 
60 to 70 times per minute; then when placed in the sun the motion 
became irregular and the count increased to as many as 120 per minute; 
the fish being placed in the shade again they were irregular and many 
at first, then dropped down to 78 per minute and became very regular ; 
the pan being again placed in the sun, the movements were only 63 
and very regular at first, but soon increased to 115 and were irregular ; 
put back in the shade they decreased to 94. The probable purpose of 
the movements of the tail was to aerate the water by keeping it 
in circulation. By May 25 the fish did not show such constant activity. 
There would be long intervals of very lttle movement, if any, but at 
this time when the tail was in motion there were 110 movements 
counted per minute. 
The night of May 25 the fish was left in the shallow pan on the 
table over night, on account of the failure of the water supply, and 
the next morning the sun had! been shining upon it for some time until 
the water was almost hot. The fish was stretched out on its back with 
its mouth wide open, and showed no signs of life whatever. The water 
was cooled gradually, and within an hour the fish was as active as 
ever. 
As the shark grew larger the activity decreased decidedly. By 
June 7 it was very inactive. Immediately after it was transferred from 
the aquarium into a glass jar, there were counted 125 movements per 
minute of the tail, and then all motion ceased until the fish was 
placed in the sun, when the activity was resumed. The light of the 
sun seemed always to increase the activity. When the egg case was 
handled or poked the fish would curl its tail around the yolk, then 
remain quiet. By June 17 the tip of the tail when curled around the 
yolk would reach the tip of the snout. During the last two months 
of its existence in the egg case, the fish was most inactive and the mouth 
movements were not always perceptible. At such times it was doubted 
if the fish were still alive. It was usually, however, with the exception 
of the last two weeks, sensitive to a jar of any kind. There was 
evidently more activity than was observed, for the head of the fish 
was not always in the same end of the case. 
