260 THE ZOOLOGIST. 



Hyodontid^e. 

 The lapillus of Hyodon alosoides is shown enlarged (fig. 5). 

 It is fairly developed for the size of the fish. 



The following fishes to be described do not belong to those 

 in which the lapillus is the largest of their otoliths : — 



Elopidje. 



Megalops atlanticus (the Tarpon) has a very well developed 

 lapillus (fig. 6), of roughly circular outline, with a dent in part 

 of it. 



OSTEOGLOSSID.E. 



The only specimen of a lapillus obtained in this family was 

 got from the head of Osteoglossum bicirrhosum, the " Aroowana " 

 of British Guiana ; it is a small stone of triangular shape (fig. 7). 



Ostariophysi. 

 The Siluridce have been dealt with above. The lapillus in 

 the families of the Characinidce and Cyprinidce occupies the 

 second place in size of their three otoliths. It is generally of a 

 fair size ; in some cases it may even be classed as large. 



Characinid.^. 

 Myletes ellipticus, the " Pacu" of British Guiana (fig. 8), has 

 a lapillus of fair size, enabling the lines of growth to be distinctly 

 traced. The lapillus of Macrodon trahira, the "Haimara" 

 of British Guiana, is of elongated shape. That of Erythrinus 

 salmoneus, called the " Yarrow " in British Guiana, assimilates 

 more in shape to that of Myletes. 



Cyprinidce. 



Leuciscus cephalus (the Chub) has a particularly solid lapillus 

 (fig. 9) which has two little projections, one terminating as a 

 slight hook. An extra lapillus was found in the right half 

 of the cranium of a Leuciscus dobula (the Dace) ; in a specimen 

 examined it is mentioned as being most abnormal. There were 

 two lapilli in the labyrinth of the right side and one in that of 

 the left side. 



Apodes. 



Murcenesox talabon, called the " Koolaree " by the Tamil 

 fishermen at Madras (fig. 10), has a well-developed lapillus, 



