AUSTRALIAN SNAKES. S5 



" The shields of the head differ so much in their arrangement from 

 those of other snakes, that a snake may be recognized as a marine species 

 by an inspection of the head only. The large nasal shields occupy the 

 upper anterior part of tlie snout, and are generally contiguous, replacing 

 the anterior frontals, which are absent ; the single pair of small frontals 

 are homologous with the posterior frontals of other snakes. There is a 

 vertical, a pair of superciliaries, and another of occipitals, one ocular, and 

 one or two postoculars ; the number of the latter is rather constant in the 

 same species. Loreal, none. The labials are somewhat irregularly arranged, 

 frequently subdivided, especially the posterior; in most of the species, 

 small pieces, nearest to the labial margin, are detached from the lower 

 labials. There is a triangiilar mental shield in front of the lower jaw, 

 behind which the first pair of lower labials form a suture together ; one or 

 two pairs of chin-shields follow. Several Sea Snakes are distinguished by 

 having some or all of the head-shields broken up into smaller irregular 

 pieces, whilst Platurits differs from all others in an arrangement of the 

 shields which is extremely similar to that in the Elapidce. The Sea Snakes 

 shed their skin very frequently, and the skin peels off in pieces as in the 

 Lizards, and not as in the Fresh-water Serpents, in which the integuments 

 come off entire. 



" Several species are remarkable for the extremely slender and pro- 

 longed anterior part of the body, for which we use the term ' neck,' and 

 which terminates in a very small head. These snakes can hardly form a 

 separate genus, as we find a most complete transition from them to the 

 forms with thick and short body. The extreme forms must differ consider- 

 ably in their habits, but no observations on tlxis point are on record. 



" The eye is small, with round pupil, which is so much contracted 

 by the light when the snake is taken out of the water, that tlie animal 

 becomes blinded, and is unable to hit any object it wants to strike. The 

 tongue is short, and the sheath in which it lies concealed opens near to the 

 front margin of the lower jaw ; scarcely more than the two terminating 

 points are exserted from the, mouth when the animal is in the water. The 

 mouth shuts in a somewhat different way from that in other snakes, the 

 middle of the rostral shield being produced downwards into a smaU lobule, 

 which prevents the water from enterinir the mouth ; this lobe is most 



