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). 



y 



Fig. 6. — Head ol Ichthyosaurus 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.) 



