
MONSTROSITIES AMONG TROUT. 289 
cle which decreases every day as he grows larger. After 
some days he is large enough to swim about with the vesicle 
under him, and at the end of forty to fifty days the sac is no 
longer to be seen, and the fish swims freely about. 
All fish, however, are not perfect and oftentimes deformed 
ones are met with. Sometimes, instead of there being one 
fish only attached to an umbilical vesicle, there are two; 
not two separate ones, but two heads attached to one body, 
or two bodies attached to one tail, as Fig.47. Fig. 48. 
shown in Figs. 47 and 48. This curious ó 
. Partial duplication of the fish takes place 
in the egg long before it is hatched, and 
is due, probably, to a bifurcation of the 
furrow around which the backbone of the 
fish is formed. The cells of the thick- 
ened oval spot, instead of forming one 
Straight furrow, for some reason or other 
= form one in the shape of a Y. Two backbones form around 
the two branches, with two heads, while one tail has to do 
for both. 
As far as has been observed it is always the anterior part 
Which is duplicated. No one body with two tails has been 
found, The tail remains single while the head and body are 
doubled; and this duplication varies from a partial division 
Of the head only to two nearly complete fish, with different 
brains, and hearts, and stomachs, and whose hearts do not 
even beat together, though the circulation in the tail must 
be common to both. On the other hand the head alone may 
8 
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Pletely Separated ; they looked something like a figure of 8 
on its side, Generally one of the half fish is larger and 
ithstanding the appt- — 
C rt of the smaller one to go somewhere else. p ex 
NATURALIST, VOL. III. 37. a 

tonger than the other, as seen in Fig. 48, and carries the — 

