VI. 



Marine Snakes. 



As in the case of the IMammaha, in which group we find a grada- 

 tional series from amphibious to absokitely marine animals 

 through such types as the Sea-Otters, tlie Eared Seals, the true 

 Seals to the Sirenians and Cetaceans, the Reptiles present us with 

 examples of almost every degree of adaptation to marine life. The 

 Galapagos Iguana, living on land, but entering the sea for feeding on 

 sea-weeds; the estuarine Crocodiles and Trionychoids, occasionally 

 wandering miles out at sea, and of which Crocodilus porosus and 

 Pelochelys are living representatives ; the Turtles and Leatherbacks, 

 essentially marine forms, which are, however, compelled to resort to 

 land to deposit their eggs ; the extinct viviparous Plesiosaurs and 

 Ichthyosaurs are well-known exaiiiples. But no better instance of 

 gradual modification from terrestrial into marine forms could be 

 found than in the Ophidia living at the present day, among which 

 also are to be found the only recent reptilian types that, being 

 viviparous, never leave the water. These snakes are the Hydrophids, 

 or Sea-snakes, and it is with the state of our knowledge of these and 

 some other snakes allied to them in their mode of life, that it is 

 proposed to deal in the present review. 



From the time of Schlegel (15) and Dumeril and Bibron (5) 

 down to the present day, the Hydrophids, or poisonous marine 

 snakes, have almost universally been regarded as a distinct and per- 

 fectly natural family. Their affinity to the Elapidae, or poisonous 

 terrestrial colubrine snakes had not been overlooked, nor could have 

 been, considering the very striking resemblance which one of them, 

 Plaiunis, bears to Elaps and BuNgayns. But the whole classification 

 of snakes was most artificial, especially when, as has been so often the 

 case, the division into poisonous and non-poisonous groups primed all 

 others. In the recently-published volume of Blanford's Fauna of 

 India deahng with the Reptiles (3) I have abandoned the character 

 of the dentition in the definition of families, and the great group 

 Colubridae is divided into three parallel series : — The Aglypha, in 

 which all the teeth are solid ; tlie Opisthoglypha, with posterioi: 

 grooved fangs ; and the Proteroglypha, with anterior grooved 

 fangs. The Hydrophids naturally find their place in the latter 

 division, and, although they are placed together as a sub-family 

 near the Elapinae, I am far from satisfied that such an arrangement 



