132 THE ZOOLOGIST. 



Cyprinims. 

 This, the Carp family, like the latter two families, has the 

 sacculus embedded in a bony cavity, and the conditions are very 

 similar, except that with the Cyprinidce there is no external 

 evidence of the sacculus, nor does the recess in which the lapillus 

 rests show prominently on the outside.* 



Silurhxe (the Cat fishes). 

 This family also has its sacculus embedded in bone, as have 

 the last three noted above. The lapillus, however, is the largest 

 otolith, and in some of the Arius t species it is a very large stone, 

 and consequently has a very large recess in the inside of the 

 skull to accommodate it. This stone can be lifted out of its 

 recess without much or any cutting away of bone. Externally 

 the situation of the lapillus can be judged by a smooth swelling 

 prominence of bone over it. 



Loricariid^e. 

 Plecostomus bicirrhosus (called the "Sea Hussar" in Deme- 

 rara ; it is, however, a freshwater fish) has the ear labyrinth 

 lying open in a double cavity at the side of the skull quite 

 different to the boxed-in condition in the Siluridce. As with them 

 the lapillus is the largest otolith (fig. II., 7) ; the difference in 

 size was made up by the more solid build of the lapillus, which 

 does not come out in the photograph. 



Aspredinioe. 

 In Aspredo sicuephorus the bone had to be cut away to get 

 out the sacculus. The asteriscus is the largest of the otoliths. 



Apodes. 

 In Anguilla vulgaris (the Eel) the position of the otoliths is 

 revealed externally by two very slight swellings of thin bone. 

 Myrus vulgaris, a Mediterranean Eel, has the sacculus in a 

 cradle-like cavity, from which it could be lifted out. The lapillus 

 in this fish is not quite like the usual shape of this stone ; it has 



* For illustrations of the asterisci of some Carps, see 'Zoologist,' 

 1910, p. 3, figs. 20, 21, 22, 23 ; see also ' Zoologist,' 1910, p. 293, fig. 16. The 

 splinter-like sagitta is faintly visible. 



f See « Zoologist,' 1910, p. 293, fig. 19, and p. 294, pi. ii., fig. 4. 



