14 THE HISTORY OF CREATION. 
covered by membrane, so that no ray of light can enter, 
and they can never see.- Such eyes, without the function 
of sight, are found in several species of moles and mice which 
live underground, in serpents and lizards, in amphibious 
animals (Proteus, Czecilia), and in fishes; also in numerous 
invertebrate animals, which pass their lives in the dark, 
as do many beetles, crabs, snails, worms, ete. 
An abundance of the most interesting examples of rudi- 
mentary organs is furnished by Comparative Osteology, or 
the study of the skeletons of vertebrate animals, one of the 
most attractive branches of Comparative Anatomy. In most 
of the vertebrate animals we find two pairs of limbs on the 
body, a pair of fore-legs and a pair of hind-legs. Very often, 
however, one or the other pair is imperfect; it is seldom 
that both are, as in the case of serpents and some varieties of 
eel-like fish. But some serpents, viz. the giant serpents (Boa, 
Python), have still in the hinder portion of the body some 
useless little bones, which are the remains of lost hind-legs. 
In like manner the mammals of the whale tribe (Cetacea), 
which have only fore-legs fully developed (breast-fins), have 
further back in their body another pair of utterly superfluous 
bones, which are remnants of undeveloped hind-legs. The 
same thing occurs in many genuine fishes, in which the 
hind-legs have in like manner been lost. 
Again, in our slow-worm (Anguis), and in some other 
lizards, no fore-legs exist, although they have a perfect 
shoulder apparatus within their bodies, which should serve 
as a means of affixing the legs. Moreover, in various ver- 
tebrate animals, the single bones of both pairs of legs are 
found in all the different stages of imperfection, and often 
the degenerate bones and those muscles belonging to them 
