88 AIJSTEALIAN SNAKES. 



Synopsis of the Genera. 



A . Ventral shields well developed, flat. 



Two pairs of frontal shields ... ... ... ... ... ... Platunis. 



B. Ventral shields well developed, icith a median ridge. 



Scales imbricate ... ... ... ... ... ... ... Aipysiirus. 



C. Ventral shields large, tvifh a very slight median ridge. 



Labial shields reduced to three above and below ; scales imbricate, 



strongly tuberculated ... ... ... ... ... ... Emydocephdiis. 



D. Ventral shields narrow, or rudimentary, or absent. 



* Nasals separated hy frontal shields. 



Ventral shields distinct to the vent ... ... ... ... ... Disteira. 



**NasaIs contiguous. 



Head covered with scales behind ... ... ... ... ... Acalypfus. 



Head short or of moderate length, entirely shielded ; lower jaw 



without notch in front ... ... ... ... ... ... Hydrophis. 



Head of moderate length, entirely shielded ; lower jaw deeply 



notched iu front ... ... ... ... ... ... ... Enhydrina. 



Snout very long, spatulate ... ... ... ... ... ... Felamis. 



PIjA.TTJEUS, Latr. 



Body subcylindi'ical, of moderate length. Shields of the head 

 subnormal in number and arrangement ; nostrils lateral, in a single 

 nasal shield, both nasals being separated from each other by a pair of 

 anterior frontals. Scales imbricate, smooth ; ventral shields well developed, 

 tail with two series of subcaudals. 



This genus approaches the Land Snakes in several characters. 

 The shields of the head are very regvilarly disposed : there are two pairs of 

 frontals, frequently with an azygos shield between the hind pair. The 

 nostril is lateral, piercing a narrow nasal shield ; loreal absent. One pre 

 and two post oculars. Seven upper labials, the third and fourth of which 

 enter the orbit ; temporals scale-like 1 + 2 + 3. The throat is covered by 

 two pairs of chin-shields anteriorly and by scales posteriorly, the ventrals 

 commencing at some distance behind the head. The scales are regularly 

 imbricate, smooth, short, slightly rounded behind ; the number of longi- 

 tudinal sei'ies on the body varies much, from nineteen to twenty-five, in 

 diiferent individuals, without affording a character for specific distinction ; 

 it is more constant on the front part of the trunk. The ventral shields 



