NOTICES OF NEW BOOKS. 73 



those of the Ichthyosaurs and Plesiosaurs, were quite inadequate 

 for support on the land, where, though they might have moved 

 in a serpentine way, our author thinks they never went 

 voluntarily. This is inconsistent with oviparous habits ; but, 

 after all, since Eels can move on shore and even travel some 

 distance thereon, there is no reason why these air-breathing 

 creatures could not have done as much. Their remains are 

 so well preserved that even the existence of scales, although 

 very small ones, is substantiated, and even bands of pigment 

 have been traced in one specimen Professor Williston has 

 examined. The shape of the head, as restored, suggests that of 

 the Sea-Eels of the Mursenoid type, known to be some of the 

 most ferocious and aggressive of fishes, by modern experience as 

 well as by the tales of wealthy and wicked Komans who used 

 to throw delinquent slaves to their pet Mursenas. Professor 

 Williston considers these ancient Sea- Serpents to be "real 

 Lizards, differing less from the living monitor Lizards than do the 

 monitors from some other Land Lizards, especially the Amphis- 

 baenas and Chamseleons," and he remarks that Adrian Camper 

 pointed out their real relationship more than a century ago. 



Though not absolutely certainly a true Mosasaur, the recently 

 discovered genus Globidens deserves mention on account of its 

 extraordinary teeth, which, according to the life-size figure, had 

 crowns of the size and shape of Barcelona nuts, indicating a diet 

 of shellfish rather than of fishes proper. 



Turning to more familiar types of reptiles, it is noteworthy 

 that all the highly-specialized marine Crocodiles or Thalattosuchia 

 have become extinct, while the semi-terrestrial Crocodiles and 

 Alligators remain ; specialization in reptiles seems very uni- 

 formly to have led to extinction. 



The accounts of water-reptiles of the present are far less 

 satisfactory than those of the ancient forms. Much more might 

 have been said of the Sea-Snakes, the only large group of 

 marine reptiles to-day, especially with regard to the genus 

 Platurus, which forms a perfect link with Land- Snakes, and 

 whose members often come on shore, unlike all the rest; and 

 with regard to the curious parallelism in development between 

 these Snakes and the Plesiosaurs, some being stout and of 

 nearly uniform calibre, while others taper extraordinarily in the 

 Zool. 4th ser. vol. XIX., February, 1915. <j 



