292 THE ZOOLOGIST. 



COMPARISONS OF OTOLITHS FOUND IN FISHES. 

 By Colonel C. E. Shepherd. 



Facts in connection with otoliths are unfortunately not 

 recorded in sufficient numbers to make it possible to use such 

 facts for any deductions as to the uses of these stones being 

 made, even if it be eventually found that such deductions could 

 be made. It would be well then to record facts, as they become 

 known, connoting the life habits of a fish and its otolith, and to 

 compare, when possible, the size of these stones in different 

 fishes, more especially when their habits are similar, and even 

 when totally dissimilar. Again, the otolith, whilst maintaining 

 its family resemblance, is yet so different in different families 

 that this lends further interest to the subject. 



In a former paper* it was pointed out that the size of the 

 fish established no corresponding rule that its otolith would be 

 larger or smaller than that of another fish of a different family, 

 but of a larger or smaller size. The Smelt, Osmerus eperlanus, 

 has a larger otolith (Plate I. fig. 13), though it is a smaller fish, 

 than that of Anxis rochei, fig. 2, on the same plate. The plate 

 shows the otoliths, natural size. 



This comparison as to the size of the otolith with the size of 

 the fish, although sufficiently obvious in the above-mentioned 

 case, hardly admits of definite accuracy, but is rather one that 

 strikes the eye when dissecting out an otolith — e.g. the otoliths 

 in Plate I. fig. 1, from a Pelamys sarda, which was 28 in. long, 

 and fig. 2 from an Auxis rochei that was 24 in. long, are, the 

 first comparatively and the second actually, smaller than the 

 otoliths of a Flying-fish (Exocoetus poecilopterus) that was about 

 8 in. long. It is in this manner that all the comparisons as to size 

 in this paper are made. As another contrast, we have those of 

 the Horse-Mackerel, Caranx trachurus (Plate I. fig. 7), and the 

 Bass, Morone labrax (Plate I. fig. 8) ; these fish have large otoliths, 



* In ' Knowledge and Illustrated Scientific News,' March, 1909. 



