iç)i6.] 



Fauna of the Chilka Lake ; Fish. 



445 



Length of head 



Distance between end of snout and vent 



Distance between vent and end of tail (tail) 



Length of snout . . 



Long diameter of the eye 



Interorbital space 



Length of upper jaw 



Length of lower jaw 



130 mm. 



525 

 850 



13 



6 



11 



44 

 46 



The fish is a casual visitor to the outer channel of the lake during the period of 

 maximum salinity. 



Distribution : — Indian Ocean, seas of India, Ceylon and the Malay Archipelago. 

 Also reported from Natal, Australia and Formosa. 



Family OPHICHTHYIDAE. 



Genus OPHICHTHUS, Ahl. 



Ophichthus chilkensis, sp! nov. 



(Text-figures 12, 13.) ' 



The length of the head is 177 % of the distance between the end of the snout 

 and the vent, the length of the snout is 2"5 %, the diameter of the eye is 1*25 %, the 

 length of the upper jaw is 5*6 %, the length of the lower jaw is 3-3 % , the depth {i.e. 

 the height of the body) at the gill openings is 5 % , the length of the pectoral fin is 

 4"6%, the girth behind the pectoral fins is 11*4%, the free portion of the caudal 

 extremity is 2-5 % of the same distance, which is nearly half {viz. ~) the length of the 

 tail {i.e. the length of the fish behind the vent), and nearly one- third of the total 

 length . 



The fish is round, long, and scaleless; the end of the tail projects beyond the dor- 

 sal and the anal fins ; this free portion is without even a rudiment of a caudal fin. 

 The head is slightly depressed, but the rest of the profile is even. 



The length of the head is comparatively small and is contained five and half 

 times in the distance between the end of the snout and the vent. The upper jaw is 

 much the longer, being one and a half times as long as the lower. The anterior 

 tubular nostrils are placed on the upper lip, directed downwards and are thus 

 placed on the inferior side of the end of the snout; the posterior nasal openings, 

 which are patent, are placed right in front of the eyes. The eyes are very small ; 

 they are lateral though somewhat superior; the diameter of the eye is contained 

 twice in the length of the snout; the interorbital distance, which is slightly convex, 

 is equal to the length of the snout ; the opening of the mouth is horizontal and the 

 angle of the jaws is one ,diameter of the eye behind the postorbital vertical. The 

 teeth on the vomer are globular and those on the jaw are granular; in the maxilla 

 they are arranged in two rows on each side, the innermost row being serrated; they 



The text-figures are numbered in continuation of those that appeared in Part I of the paper. 



