26 THE ZOOLOGIST. 



Elopid^e. 

 Elops saurus. The otoliths are illustrated (fig. IV., 9). 



OsTEOGLOSSIDjE. 



Arapaima gigas, called the "Pirarucu" at Manaos, on the 

 Amazon Kiver, Brazil. To this species belongs the largest of 

 freshwater fishes ; it has a corresponding otolith (fig. V., 10). 

 This is enclosed in a bony pocket that has to be cut open to 

 obtain the otolith ; there is no external indication showing site 

 of sacculus. The specimen illustrated was got from a 5 ft. 9 in. 

 fish caught in the interior of British Guiana. The rings of 

 growth of the stone are to be seen in the upper one. The hump 

 in the central part of the stone is a peculiarity special to this fish. 



Osteoglossam bicirrhosum. The otoliths shown (fig. IV., 10). 



ChIROCENTRIDjE. 



Chirocentrus dorab. Illustrated fig. V., 3. 



ostariophysi. 

 Gymnotid^e. 

 Eigenmannia virescens. Illustrated fig. IV., 5. 



Silurid^. 



Bagarius yarrellii (a freshwater Siluroid). This specimen 

 came from one of the rivers in Bengal, India. It was over six 

 feet in length ; the otoliths are conspicuously small. There was 

 no external indication either for the site of the sacculus or for 

 the position of the lapilli. The swim-bladder which, in the 

 Ostariophysi, is connected with the ear-labyrinth, is, in this fish 

 in two separate small bladders. The Weberian ossicles which 

 form the connecting-links were of good size, especially the 

 " tripus." The contrast in size between the otoliths (fig. VI., 6) 

 of B. yarrellii, and those of a salt-water Siluroid (Mluriclithys 

 gronovii, fig. VI., 7) and of a Gadus merlangus (fig. VI., 8) is 

 instructive. 



Mlurichthys gronovii, one of the so-called " Catfishes," got at 

 Demerara, British Guiana. This is allied to the Arius family, 

 and the specimen obtained was a moderate- sized fish, probably 

 some eighteen inches in length, judging by the head, which was 

 the only portion sent. The site of the lapilli, the biggest of the 

 otoliths, was shown externally by two big swellings of thin, shiny 



