THE COMMON INDIAN SNAKES. 91 



dark postocular streak is prolonged backwards to the side of the 



forebody. 



Identification. — The frontal which is partially, and the parietale 

 which are wholly broken up, furnish an easy means of knowing 

 the ijnake, but perhaps a more certain method is as follows : — A 

 snake which when laid on its back, reveals well developed ventrals 

 at least three times the breadth of the last costal row, and at the 

 same time shows three or more rows of costals on each side of the 

 ventrals will prove to bo a Homalopsid. Cerberus will be easily 

 distinguished from its near Indian relations by possessing (1) two 

 internasals, (2) 9 to 10 supralabials, and (3) 23 to 27 costal 

 rows in midbod3^ 



Haunts and habits. — It is eminently an aquatic species usually in- 

 habiting the brackish waters of tidal-rivers, crt eks, and ebtuaries. 

 Ferguson and Cantor say that it frequents fresh water alto, and 

 Cantor, Haly and Flower, all report it from the sea in clote prox- 

 imity to our coasts. 1 became acquainted with it in Baima, and 

 frequently observed it in the waters of the narrowest channels con- 

 nected with the tidal-i'iver sybtem, as well as in the river itself. I 

 frequently saw it svvimming in the ebb and Hood tides. It swims 

 powerfully usually allowing itself to be carried with the stream, 

 but it sometimes anchors itself to a convenient biimboo stake, 

 anchor rope, or submerged branch by its tail, and from this pur- 

 chase swings about in the current on the look-out for fish passing 

 by. As the tide ran out many were observed lying along the 

 branches of the trees, and bushes just above the water, and when 

 hustled dropped off into the stream below. Numbers were left 

 stranded on the mud flats left by the receding tide nud in the teak 

 yards nearly every bole harboured beneath it, some of these snakes. 

 I have seen it exhibit some intelligence in the following manner. 

 Lying extended in the length of a nearly empt}' ditch, after a 

 period of quietude, it flicks its tail round first on one side and then 

 the other in such a way as to make an unwary fish recede from the 

 rnovement towards its head, when coming within sight the fish 

 falls an easy victim to the manoeuvre. Taken at a disadvantage 

 on land it will occasionally exhibit great activity, and irj to escape. 

 When prevented from so doing it protrudes the tongue, and hisses, 

 and flattens itself on the ground. When held down by a stick it 

 will sometimes strike, and bite viciously, and under such excitement 

 emits a disagreeable odour not necessarily accompanied by a dis- 

 charge* of the cloacal contents. When picked up it wreaths itself 

 with some force around the hand. 



Its mode of progression is curious. The bodj'' is thrown for- 

 ward in a carve in advance of th^ head, and the head subsequently 

 advanced, the body being agaiti thrown forward before the snake 

 quite extends itself. It gives the impression of moving sideways. 



