SKATES. 
83 
P oceed fiom the egg-case, this more slender portion of the body 
proportionately of much greater length than in the full-grown 
imal; but by a process not much unlike that which deprives 
e tadpole altogether of its tail, the end that lies behind the 
isa tins gradually ceases to receive nourishment, and con- 
equently diminishes, so that by the time the fish has attained 
a out a fourth part of its full dimensions this part is 
e uced to a much less lengthened condition. In the gener- 
of these fishes there are on this part only two small 
roisa fins, hut there is more obscurely a slight border of 
“lembrane along the sides, and a rudiment that almost resembles 
^ n which proceeds from the second dorsal to the end. There 
also m a very few instances been discovered an elevation 
° membrane resembling a fin, on the body or disc itself, in 
or other of this family; and the circumstance has been 
eeined of sufficient importance to warrant a belief in the 
the existence of a distinct species, 
to I ’lotice of it was by Cuvier, who, however, appears 
^ lave doubted whether it was anything beyond an accidental 
ariety of a common species. But Lacepede felt no doubt on 
an'l ^ “History of Fishes” he gives a figure 
description of it under the name of Cuvier’s Ray. It 
^ since been detected in Scotland, and as a mark of a 
species IS adopted by Dr. Fleming, under the same name; but 
appears to be at this time the common opinion of naturalists 
at Cuvier’s suspicion was well founded, and that this supposed 
IS nothing more than a doubling of the surface of the skin 
® the back, and is not a sufficient mark that the fish bearing 
th ^ species. It is among what we denominate 
ta’l of this family that in some cases the true 
ai exists, in addition to the dorsal fins, and in others no 
os of any sort are found. We shall notice those more 
larticularly when we speak of the different genera. 
th’ ** J^nown, and at least among all the members of 
IS lamily found in the British Islands, all of these fishes 
des '^T their young from eggs enclosed in purses; which eggs 
exd^^ ovarian receptacle in pairs, and become 
^ 0 u ed in succession, in seasons of the year appropriate to 
^^0 species. These purses are formed of a leather-like sub- 
ance, with m general short but rather firm tendrils at the 
