LOCATION OF THE SACCULUS IN FISHES. 135 



large asteriscus of crescentic shape. The sacculus pocket is 

 open at the top, but bone has to be cut away to free the lagena. 

 In this family the sagitta is of fair size and very much curved. 



POLYNEMIDiE. 



In Polynemus tetradactylus (the " Mangoe Fish " of Calcutta, 

 where it is also called " Tapsi machli," adopting one of the 

 native names) the site of the sacculus is indicated exteriorly by 

 a slight swelling of the basi-occiput bone. The pocket containing 

 the sacculus is open at the top ; the sacculus could have been 

 easily lifted out but for the lagena portion, which runs back into 

 a bony burrow encasing it completely, and requiring to be cut 

 away to extract it. The otoliths from the right half of the head 

 are illustrated (fig. I., 4). 



Sphyr^nid^e. 

 Sphyrcena vulgaris (the "Barracuda ") has the sacculus lying 

 in a groove in the bone of the skull, which is open at the upper 

 end, a little bone, however, has to be cut away to free the 

 sacculus altogether. The otoliths in this fish lie more parallel 

 to, i. e. with less divergence from the middle line of the fish at 

 their forward end, than is the case with so many other fishes. 



Stromateid^j. 

 Stromateus niger (the Pomfret " of India) does not show 

 externally the situation of the sacculus ; inside, the sacculus is 

 in a pocket open at the top, but cased in with bone at the sides. 

 The lapillus has a marked recess in the skull for itself. 



OPHIOCEPHALIDiE. 



In Ophiocephalus punctatus the situation of the sacculi is well 

 marked by two excrescences on the under side of the basi-occiput, 

 which stand well out. 



Anabanthxe. 



In Anabas scandens (the " Climbing Perch " of India) the 

 sacculi are located in two prominent excrescences, which, when 

 the branchial arches are removed and the skull reversed, show 

 remarkably clearly. The lagena is a long prolongation of the 

 sacculus ; it has a little pocket to itself. The sagittae are fairly 

 large and solid for the size of the fish (fig. II., 2). 



