LOCATION OF THE SACCULUS IN FISHES. 133 



also a slight hook at its extremity. In Conger vulgaris (the Conger) 

 some thin but not transparent bone of the basi-oeciput shows 

 the site of the sacculus. The sagittse are large. 



Esochxe. 



Esox lucius (the Pike) has no external indication of the 

 site of the sacculus. This is contained in an open pocket from 

 which it could be easily lifted out ; it shows no distinct lagena, 

 but the asteriscus can be seen through the tissues of the sacculus ; 

 the sagitta also shows through. 



ScoPELnxE. 



In Scopelus punctatus the sagittse lie in two ovoid pockets that 

 show on the outside ; the thin bone under them permits of their 

 being seen. 



C YPRINODONTID JE . 



In Haplochilus playfairii the pockets for the sacculus are at the 

 side of the head, and two excrescences on the under side of the 

 skull show their situation. Anableps tetropthalmus (the '■• Four- 

 eyes " of British Guiana) has no outside indication of the site of 

 the sacculus ; it rests in an open cavity at the outer side of the 

 brain chamber. 



FlERASFERID.ffi. 



The comparatively large solid sagittse of Fierasfer acus, a 

 Mediterranean fish, show clearly through the transparent bone 

 underlying them. 



Gastrosteid^:. 



The " Sticklebacks " have no outside indication of the posi- 

 tion of the sacculus apparent. As may be surmised, the sagittal 

 are very minute. 



Centriscidje. 



In Centriscus scolopax (the " Trumpet Fish " or " Bellows 

 Fish ") there is no external evidence of the site of the sacculus. 

 It lies loose on the floor of the skull, with no apparent special 

 cavity for it. 



Syngnathid^;. 



Syngnathus acus (the " Pipe Fish ") has no external indica- 

 tion of the site of the sacculus. 



