CALIFORNIA FISH AND GAME. 155 
Cube of 
Cube of yolk sac 
fishes length 
Seer | | eee er ee 
ousands| 
3500 70 
Rete Phe hele ae eer, 
(ieee 16 26 16) 26°75 15 25 5 15e 2b 47149 
_ March eee May yr June July August ; 
rer) 
Fic. 40. Rate of growth of body and diminution of yolk of Swell Shark. 
Bulk of fish according to cube of length. 
SSS = = Bulk of yolk according to cube of length. 
irregular in outline, but resumed the more oval appearance about 
May 25. By July 17 the yolk seemed to be entirely absorbed, leaving 
only a small round sac at the end of the umbilical cord, which was 
only about one-half of its original 
length, and by July 28 was reduced to 
less than an eighth of an inch and gave 
the appearance of a tiny knob on the 
ventral side of the fish. After hatch- 
ing the only evidence of the cord was 
a little spot about the size of a pin head. 
The rate of growth of the fish and d 
the diminution of the yolk are shown 
in the accompanying chart. It will be 
noted that after the external yolk had 
been absorbed, about July 17, the fish fad 
continued steadily to grow, due prob- 
ably to an internal supply of yolk. 
(See diagram.) Note also that from 
April 15 to 26 there was no change in 5 
the yolk shown in the curve, probably 
due to the fact that at this time the yolk 
was changing in shape somewhat and 
becoming narrower, while the length ei 
remained constant. ete 
By May 20 the gill filaments, which pes: 
were long and kept in constant motion 
by the movements of the fish, had en- pte 
tirely disappeared. They had been 
present in each gill slit and in the spir- 
acles. Subsequent to this the breathing 
motion of the mouth was observed. 
The color of the fish in the early : Bien 
stages was a uniform whitish. On May artnfdie Disgtam, snowing, internal 
25 a few dark spots were observed on @ Solid body filled with yolk. b. 
Stomach. ec. Spiral valve. d. Um- 
the fins and by June 7, over ten weeks pilical cord. 
