THE GREAT FISH-LIZARDS. 47 
book held in the hand. But here is a creature that possessed an 
apparatus far more simple and effective than that supplied by 
the optician! Dr. Buckland, speaking of these “sclerotic plates,” 
as they are called, says they show ‘‘that the enormous eye of 
which they formed the front was an optical instrument of varied 
and prodigious power, enabling the Ichthyosaurus to descry its prey 
in the obscurity of night and in the depths of the sea.” But the 
last expression must be taken in a limited sense (see Fig. 6). 
Fic. 6.—Head of /ehthyosaurus platyodon. 
It might well be supposed that no record had been preserved 
from which we could learn anything about the nature of the skin 
of our fish-lizard ; but even this wish has been partly fulfilled, to 
the delight of all geologists. Certain specimens have been 
obtained, from the Lias of England and Germany, that show 
faithful impressions of the skin that covered the paddles. A 
specimen of this nature has lately been presented to the national 
treasure-house at South Kensington by Mr. Montague Brown. 
On the inner side of the paddle was a broad fin-like expan- 
sion, admirably adapted to obtain the full advantage of the stroke 
of the limb in swimming.? 
Speaking of the limbs, it should be mentioned that the bones 
of each finger, instead of being elongated and limited in number 
to three in each of the five fingers, are polygonal in shape and 
* Mr. Smith Woodward informs the writer that specimens have lately been 
found near Wiirtemberg, with evidence of a triangular fin on the back. Plate 
II. has been redrawn for this edition, to make it more in harmony with Dr. 
Fraas’s discoveries. (See Appendix V.) 
