158 PICTURESQUE SKETCHES 



Plesiosaur is known, from some admirably preserved 

 specimens, to have had upwards of thirty, and perhaps 

 as many as forty. In its proportions, the neck in one 

 species measures four times the length of the head, 

 and actually exceeds the entire length of the body 

 and tail. It was apparently thick and muscular 

 near the body, but gradually became slender towards 

 the head, which was small, and sometimes singular- 

 ly disproportioned in size to the other parts of the 

 animal. 



The head thus reduced in size exhibits, how- 

 ever, rather a high type of organization. It offers 

 some of the peculiarities which characterise the li- 

 zard, especially in the wide interspaces left between 

 the bones; in the existence of a strong crest along 

 the middle of the skull, indicating that the jaws 

 were worked as in lizards and not as in crocodiles ; 

 in the structure of the lower jaw ; and in the ab- 

 sence of a cross ridge on the fore part of the skull. But 

 in its general form, in the strength and size of the 

 bones of the face and jaws, in the rugged outer sur- 

 face of the bones, and in the sockets for the teeth, 

 there is a distinct and well-marked approximation 

 to the crocodile. 



In the size and position of the breathing-holes, or 

 external nostrils, we find, however, a marked and 

 interesting difference from all existing reptiles, and 

 a strong analogy to the corresponding part in animals 

 allied to the whale, offering a beautiful example of 

 adaptation of structure presented in very different 

 animals, but producing similar results and supplying 

 similar exigences. These apertures are placed near 

 the highest part of the head, where they would enable 



