811 
of the Oviviviparous Shark , &c. 
«©T them containing young sharks in all the different stages of 
their growth. The egg which is represented in the annexed 
drawing, is exactly similar to the engraving in Bqhadsch; 
when minutely examined, there is on each side of the egg a 
small slit, for the admission of salt water within the shell. 
In the latter end of October, a young dog-fish was sent me 
23 inches long, which exactly resembled the embryo in the 
egg, and proves to be the squalus canicula of Linn^us ; it 
had been feeding on the worms met with in the sand banks* 
some of which were found in its stomach. 
The oviviparous and oviparous dog -fishes, differ materially 
in the form of their stomachs. In the first, the pyloric portion 
is short and wide, in the other, long and narrow like an in- 
testine. As there are larger sharks with both these kinds of 
stomach, it is reasonable to believe they have also the same 
difference in their mode of breeding. 
The gelatinous liquid which surrounds the ova of the dog- 
fish, was found to differ exceedingly in its properties from 
other animal jellies, for when the membranous bag contain- 
ing it, was immersed in proof spirit, for the purpose of pre- 
serving the ova in their natural situation, the jelly, instead of 
coagulating, as was expected, expanded so much as to burst 
the bag. So striking a peculiarity led to a further considera- 
tion of it, and a suggestion naturally arose in my mind, that 
■there might be a similarity between it and the jelly, with 
which the ova of the frog are surrounded. I therefore re- 
quested my friend Mr. W. Brande, to examine the chemical 
properties of both these substances, and shall subjoin his 
account of them. 
That the jelly in the oviviparous dog-fish, is formed in the 
