256 SNAKES OF CEYLON. 



Identification. — Ventrals at least three times as broad as the 

 ultimate costal row, with three or more rows of costals visible 

 each side, and a rostral in contact with four or five shields will 

 indicate a Homalopsid. Cerberus is known from the other 

 genera by the disintegrated parietal shields. 



Habits. — Fluviatile, estuarine, and semi-marine. 



Food.— Fish. 



Breeding. — Viviparous . 



Poison. — Very slightly poisonous. Innocuous to man. 



Lepidosis — Rostral : Touching four shields. Internasals : A 

 pair, subtriangular with apposed bases. Prefrontals : A pair. 

 Frontal : Disintegrate posteriorly. Parietals : Disintegrate. 

 Nasals : In contact behind the rostral. The nostril slit-like 

 and superior. Loreal : Present, single. Prseoculars : One. 

 Postoculars :• Two. Temporals : Small and scale-like. Sub- 

 oculars : Present ; cutting off contact of all supralabials with 

 the eye. Supralabials. Nine or ten ; the first seven entire. 

 Infralabials : Seven. Sublinguals : Three pairs ; the median 

 and posterior oblique and quite separated by small scales. 



Costals : Longer than broad, rectiform, keeled. The verte- 

 bral row not enlarged ; the breadth of its scales about two- 

 thiids their length, and about two-thirds the ultimate row. 

 Ultimate row enlarged, the breadth of its scales subequal to 

 their length. In 23 to 29 rows at midbody. Usually six (or 

 four) rows less at a point two heads-lengths before the vent. 

 The 5th row above the ventrals is absorbed in the first two steps, 

 and the 4th at the third. Ventrals : Rounded. About three 

 times the breadth of the ultimate row. Anal : Divided. 

 Subcaudals : Divided. 



Dentition. — Maxilla : Diacranterian. Praecranterian, kuma- 

 todont. Cranterian, not enlarged ; obliquely set ; grooved 

 on their anterior faces. Palatine : Anododont, isodont, 

 Pterygoid : Anododont, scaphiodont. Mandibular : Anododont, 

 kumatodont. 



Distribution. — India to Indo -China. Ceylon, Andamans, 

 Nicobars, Malay Archipelago to the Philippines, and North 

 Australia. Three species are known, one of which, viz., 

 rhyncJiops occurs in Ceylon, 



