SHARKS AMD RAY-FISHES. 
9 
history of this order of fishes, to "which we will address our 
attention, and this is the manner in which they produce 
their young. The males are distinguished from the females in 
a way very unlike any that is seen in other families of fishes, 
and this is by being in possession of jointed organs that are 
attached to the body, close to the ventral fins ; and which are 
usually known by the name of claspers, but of which the precise 
use is little understood, although we may suppose that they have 
some connection with the offices of love. Neither the Sharks 
nor Bays possess what can he termed a milt or roe, as in bony 
. . es, ut they have something equivalent to those organs, which 
IS tound studded with eggs in various stages of growth; and as 
these escape from their primitive station they descend to their 
IH'oper receptacle, which is divided into two chambers, where 
t ey wait for theii final development. The larger number of 
M s are found to hatch their young within themselves, but 
wit out any adhesion to the organ in which they lie; and the 
only exception to^ this internal hatching, at least as it is appli- 
ca e to the British genera, is found in the genus Scyllium, or 
groun haiks, of which we will speak particularly when we 
describe the habits of that race. The Rays, without any ex- 
ception t at is known, resemble the ground Sharks, in excluding 
t ® before the final perfection of their young. 
Of the first named, or viviparous Sharks, the eggs descend 
rom the ovary either at once, as in several species, or in long 
succession, as is the case with the Picked Dogfish; and in the 
double receptacle into which they are now received they obtain 
a lather rapid development, in the progress of which they 
offer an interesting spectacle to a close observer, as being even 
more remarkable than that which takes place in the egg of a 
The slight membranous covering which at first enveloped in 
one mass the embryo fish, and the proper egg which is to supply 
It with sustenance during the period of its interuterine growth, 
has been burst asunder by extension, and the young fish lies 
in Its receptacle awaiting the changes that shall prepare it for 
being launched into the waters of the ocean. But during this 
stage of inaction a temporary substitute is required for the 
purification of the blood, in place of the more perfect gills 
which will have to perform this function in their future con- 
VOL. I. 
