124 WATER REPTILES OF THE PAST AND PRESENT 



they were inclosed within their egg-covering at the time of their 

 death. Some of these embryos measure as much as twenty 

 inches in length. 



Because the ichthyosaurs were born alive, and because so many 

 of their skeletons are found with their various parts in orderly 

 relation to each other, it is inferred with much probability that they 

 were inhabitants, in large part at least, if not exclusively, of the 

 open and deeper oceans. Had they been oviparous they must 

 necessarily have laid their eggs upon the beaches, since no reptiles 

 of the present time lay eggs in the water, and we have no other indi- 

 cations that the reptiles of the past have ever done so. And such 

 habits would necessitate the periodical return to land. Had they 

 been denizens of shallow waters, like the mosasaurs and plesiosaurs 

 for the most part, their skeletons must surely have been disturbed 

 by the currents and tides, as also by predaceous fishes, breaking 

 up or displacing them or carrying away their bones. In shallow 

 waters, also, the decomposing bodies would have been more liable 

 to despoliation by the many scavengers of the seas. 



The ichthyosaurs must have been quite helpless upon land, 

 their limbs being of little more use for locomotion than are the fins 

 of fishes. Breathing air as they did, they were of course not 

 suffocated when exposed, unless, as is the case with the whales, 

 the feeble attachment of the ribs prevented the action of the res- 

 piratory muscles. If accidentally thrown upon the beaches, they 

 doubtless were able to return to their home element more easily than 

 the fishes can, by flopping, wriggling, and turning. As we have 

 seen, the food consisted in part, perhaps the larger part, of small 

 invertebrates, and because the bones of the lower jaws were closely 

 united, permitting little or none of that expansion so characteris- 

 tic of the snakes, all their prey must have been of relatively small 

 size. In habit the ichthyosaurs were doubtless, like the dolphins 

 and gavials, inoffensive and harmless, so far as animals of larger 

 size were concerned. The abundance of their remains often found 

 in restricted localities, while deposits of like age and character not 

 far distant may be almost free from them, suggests that in all 

 probability the ichthyosaurs, or the later ones at least, were more 

 or less gregarious in habit as are the sea-mammals. They probably 



