L/'/t' /';/ the Ancient Seas 315 



that they lived almost entirely on those animals. That 

 they were very dangerous enemies of the other larger 

 forms which inhabited the seas with them is evident 

 from their structure; the powerful tail especially must 

 have made them active in their movements, and this 

 together with their predacious habits would tend to 

 make them unusually formidable. The largest known 

 ichthyosaurian had a head measuring about six and one 

 half feet long; when found, the greater part of the 

 body of this animal was missing, but it is probable that 

 the head represents a total length of more than thirty- 

 three feet. 



In the same family as the foregoing creatures, and 

 living about the same time, was another genus of sea- 

 dwelling reptiles which left a considerable number of 

 well-preserved remains in the various deposits through- 

 out the world. These were the plesiosaurians. None 

 of them seem to have attained to the length of the 

 ichthyosaurians; but it is certain that they were quite 

 as voracious, if not so formidable. They lived on 

 fishes, cuttlefishes, and other animal prey. The fossil- 

 ized stomach contents of some of the later types show 

 that they swallowed stones for digestive purposes, just 

 as do the crocodiles of the present day. These strange 

 creatures are considered by some naturalists to be the 

 most singular in structure and in character the most 

 anomalous of any that have been discovered amidst the 

 ruins of former ages. Attached to a slender neck of 

 enormous length was a small head, the jaws of which 

 were filled with sharp gaviallike teeth. The snout was 

 short, but the mouth was capable of gaping very wide. 

 Its tall was somewhat short and apparently not used to 



