^^ SHARKS AND 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 Rays possess what can be termed a milt or roe, as in bony 

 fishes; but they have something equivalent to those organs, which 

 is found studded with eggs in various stages of growth; and as 

 these escape from their primitive station they descend to their 

 proper receptacle, which is divided into two chambers, where 

 they wait for their final development. The larger number of 

 Sharks are found to hatch their young within themselves, but 

 without any adhesion to the organ in which they lie; and the 

 only exception to this 'internal hatching, at least as it is appli- 

 cable to the British genera, is found in the genus ScijlUum, or 

 ground Sharks, of which we will speak particularly when we 

 describe the habits of that race. The Rays, without any ex- 

 ception that is known, resemble the ground Sharks, in excluding 

 the e^^ before the final perfection of their young. 



Of the first named, or viviparous Sharks, the eggs descend 

 from 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 rather 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 

 bird. 



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. C 



