292 
CARTILAGINEI. 
of maxillaries and intermaxillaries, are reduced, 
throughout the Order, to mere rudiments con- 
cealed beneath the skin : and the functions proper 
to them are performed by other bones of the 
mouth, as the palatals, and the vomer. 
Most persons who have ever looked at the 
backbone of any ordinary fish that is brought to 
table, — a Mackerel, a Cod, or a Salmon, — are 
aware that each vertebra is hollowed into a 
funnel-shaped cavity on each face, which is filled 
with a gelatinous substance : and that the centre 
is pierced with a slender hole, through which this 
jelly passes, thus forming a continuous cord, 
dilated and contracted alternately, throughout 
the spine. In many species of this Order the 
gelatinous cord varies very little in its diameter ; 
and in some, the central tube of communication 
is so much enlarged as to reduce the solid part to 
a mere ring of cartilage. 
It is observable that this Order presents us 
wdth some fishes having peculiarities of organi- 
zation of a higher type than is found elsewhere 
in the whole Class, exhibiting a close affinity 
with the Reptiles ; and even making a distinct 
approach to the Cetaceous Mammalia. ‘‘The 
viviparous Sharks,” says the learned author of 
Horag Entomologies, “ such as the Basking- 
Shark {Selache maxima, Cuv.), with their ear 
more perfectly organized than that of other fishes, 
and their body destitute of scales, the particular 
disposition of their fins, and their closed branchice, 
all indicate at what place we are to enter among 
the fishes upon leaving the Cetaceous quadru- 
peds.”^ 
Hor. Entom. 272. 
