AUSTRALIAN SNAKES. 
L 
x1 
“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 the 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 triangular 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 Platurus differs from all others in an arrangement of the 
shields which is extremely similar to that in the Elapide. 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 this 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 the 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 small lobule, 
which prevents the water from entering the mouth; this lobe is most 
