158 
THE GEOLOGICAL MIDDLE AGE. 
to understand the structural relations of the lat- 
tei > their true position in the Animal King- 
dom, when those which preceded them are better 
understood. One of the most 
remarkable and numerous of 
these Triassic Reptiles seems to 
have been an animal called La- 
byrinthodon, and resembling, in 
the form of the head, and in 
the two articulating surfaces at 
the juncture of the bead with 
the backbone, the Frogs and 
Salamanders, though its teeth 
are like those of a Crocodile. 
As yet nothing has been found 
of these animals except the 
head, — neither the backbone 
nor the limbs ; so that little is 
known of their general struct- 
ure. 
1 lie Ichthyosauri (Figure lj 
must have been very laro’e 
seven or eight feet being the 
ordinary length, while speci- 
niens measuring from twenty 
to thirty feet are not uncom- 
mon. The large head is pointed, like that of the 
i orpoi.se; the jaws contain a number of conical 
teelh, of reptilian form and character; the eye- 
