INTEODUCTIOX. xvii 



that of a small lien's egg downwards, and no doubt representing the fossilized 

 contents of the stomach. The stones are of various kinds, including quartz, 

 sandstone, and gneiss ; for the most part they are rather angular with the angles 

 somewhat rounded off. The mass in which the stones are embedded consists 

 mainly of angular grains of quartz-sand of various sizes, and mingled with these 

 are numerous hooks from the arms of Cuttle-fishes, with black masses which 

 show the characteristic structure of portions of the ink-bags of the same creatures. 

 It is notable that the stomach does not seem to contain any of the hard " guards " 

 of the Belemnite shell, so that probably the animal either bit off the soft anterior 

 portion of its prey or perhaps, as Mr. Crick has suggested, fed on some such form 

 as Geoteuthis, in which the hard parts were not present. 



Although no doubt both the long-necked Elasmosaurs and the short-necked 

 Pliosaurs could catch their prey on the surface, the former probably fed largely 

 on animals living at the bottom, reaching down with their long necks much as 

 do swans. At least, this manner of feeding would account for the tendency to 

 increase the length of the neck in this group, for such increase would be of 

 considerable advantage to the animals in widening their radius of action in the 

 search for food. The longest-necked Plesiosaur at present known is Elasmosaurus 

 itself, from the Cretaceous of Kansas : in this reptile, as already noted, there were 

 no less than 76 cervical vertebrae, the total length of the neck being about 

 twenty-three feet, while the body was only about nine feet long. Some such 

 explanation as that suggested above seems necessary to account for the otherwise 

 apparently disproportionate development of this part of the body. The comparative 

 lack of flexibility of the neck, especially of the posterior portion, in some of these 

 reptiles would not be any disadvantage, because the whole body would probably 

 be tilted up much as it is in the case of birds feeding in a similar way. 



Any discussion as to the relationship of the Sauropterygia to the other reptiles is 

 deferred till the Pliosaurs have been described. 



CHARLES W. ANDREWS. 



Department of Geology, 

 July 1910. 



