Oct., 1891 . 
DRAGONS OF THE PRIME. 
219 
correspond to those of the limbs of a frog, of a crocodile (Fig. 2), 
or of a man, but are simpler in shape : thus, in the fore-paddle, 
there is an upper bone which corresponds to that in the 
upper part of the arm, namely, the humerus ; on it follow two 
shorter bones corresponding to those in the fore-arm ; then 
come a number of bones which answer to those of the wrist, 
the palm, and the fingers. In some cases there were as many 
as six, seven, eight, or even nine rows of finger bones. The 
paddle of Ichthyosaurus, then, in its composition was like the 
fore-limb of a crocodile, but different in this that the fingers 
were not enclosed in separate stalls of skin as our fingers are, 
but were all enclosed in the same sheet of skin, so that the 
paddle was like a hand in a mitten, without any thumb, not 
like a hand in a glove. 
Of the two pairs of paddles, the front ones are the larger, 
and were used for driving the animal both upwards and 
downwards in the water ; the hinder paddles were used, 
perhaps, for driving upwards only. This seems probable, 
because in the whales and porpoises there are no hind-limbs, 
but the tail has a broad, horizontal fin by means of which 
the animals are driven upwards. Hind limbs, therefore, are 
not required for this purpose. As in the whales, so also in 
Ichthyosaurus, it was very necessary that an upward move¬ 
ment could easily and quickly be made, since the creature, 
like all reptiles, possessed lungs, and required to ascend to the 
surface of' the water to breathe air. 
In relation to the importance of the limbs in driving the 
animal up to the surface, is the strength and extent of the 
shoulder-girdle. Its strength of structure prevented the 
lungs from being compressed by the great weight of water 
when the animal was deep below the surface, while the broad 
bones of which it is composed presented a fit surface for the 
attachment of the powerful muscles by which the paddles 
were moved. 
If now we look at the jaws (Fig. 4), we find that they carry 
numerous pointed teeth, which have sharp cutting edges. 
Ichthyosaurus, no doubt, was a very ferocious and greedy fellow, 
and preyed on the numerous fishes and cuttles that swam 
about in the Mesozoic waters, seizing them with his jaws. 
Now, in order that he might seize his food easily and with cer¬ 
tainty, his jaws are long and slender, and very light, so that 
they could easily be snapped together. But it is plain, that 
the strain on the lower jaw when a large powerful animal 
was seized and retained would be very great, and would 
certainly have broken it had it been made of a single bone. 
In relation, however, to the strains and shocks which it had to 
