THE GREAT FISH-LIZARDS 69 



prostrate, with its under side resting or dragging on the ground 

 somewhat after the manner of a turtle. 



It is a curious fact that this bony arch resembles the same part 

 in those singular and problematical mammals, the Echidna and 

 the Platypus, or duck-mole. 



The enormous magnitude and peculiar construction of the eye 

 are highly interesting features. The expanded pupil must have 

 allowed of the admittance of a large quantity of light, so that the 

 creature possessed great powers of vision. 



The organic remains associated with fish-lizards tell us that 

 they inhabited waters of moderate depth, such as prevails near a 

 coast-line or among coral islands. Moreover, an air-breathing 

 creature would obviously be unable to live in " the depths of the 

 sea ; " for it would take a long time to get to the surface for a 

 fresh supply of air. 



Perhaps no part of the skeleton is more interesting than the 

 curious circular series of bony plates surrounding the iris and 

 pupil of the eye. The eyes of many fishes are defended by a 

 bony covering consisting of two pieces ; but a circle of bony over- 

 lapping plates is now only found in the eyes of turtles, tortoises, 

 lizards, and birds, and some alligators. This elaborate apparatus 

 must have been of some special use ; the question is What 

 service or services did it perform ? Here, again, we find answers 

 suggested by Owen and Buckland. It would aid, they say, in 

 protecting the eye-ball from the waves of the sea when the 

 creature rose to the surface, as well as from the pressure of the 

 water when it dived down to the bottom for even at a slight 

 depth pressure increases, as divers know. 



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, 



