SEA-SNAKES. 



225 



Family V. HYDROPHiDiE. 



(Sea-snakes.) 



The number of species contained in this group 

 is not great, and they have all been made known 

 to science within a comparatively recent period. 

 They are not of large size ; their forms are slen- 

 der ; but they are most readily distinguished by 

 the oar-like form of their tail, which organ, as 

 well as the posterior part of the body, is flattened 

 vertically, so as greatly to resemble that of an 

 eel, and in some cases, is dilated in the same 

 direction. The nostrils 

 are closed by a scale, 

 and, as well as the eyes, 

 are so situated as to have 

 a vertical aspect ; the 

 pupils are circular, indi- 

 cating diurnal activity ; 

 the ventral plates, formed 

 of two united scales, are 

 narrow, and occupy only 

 the central line of the 

 belly instead of its whole «^^° ^^^ ^'^^^ °^ «^^ ^^^^^'• 

 breadth ; there are no spurs, nor any vestiges of 

 limbs. 



These Marine Snakes are highly venomous, 

 though their teeth display a structure somewhat 

 differing from that of the fangs of the Viperadce 

 " The character," remarks Professor Owen, 

 " most commonly adduced from the dental system 

 as distinguishing the venomous from the non- 

 venomous Serpents, is, that the former have two, 



Q 



