136 FISH HATCHIXG. 



contents of the umbilical vesicle into the 

 body of the fish, the one decreasing as the 

 other increases — as ^\t11 as the curious phe- 

 nomenon of this vesicle having a double 

 covering ; secondly, the perpetual motion of 

 the pectoral fins. I therefore requested my 

 friend, Mr. Henry Hancock, F.Z.S., F.C.S., 

 &c., to undertake a microscopic examina- 

 tion of them, and this gentleman has kindly 

 sent me for publication the following inte- 

 resting and able paper on the subject, in 

 which several new and important facts are 

 elucidated. 



SOME EE]MAEKS RELATIVE TO YOUNG SALMOK 

 By HE^'RY J. B. Hancock, E.Z.S., E.C.S. 



In January of this present year, it w^as 

 suggested to the author that he should inves- 



