4782 Fishes. 



IV. I shall now place before my readers, as briefly as I can, the 

 result of multiplied researches into this subject. As a transcendental 

 anatomist, I naturally commence .with the dentition of the young ; in 

 its history we have the key to the numerous exceptions, rendering 

 M. Valenciennes' law inapplicable, and to the anomalies and embar- 

 rassments of naturalists and others. If we commence the inquiry into 

 the history of the dentition of the Salmonidae at a stage of their 

 growth when the size of the teeth admits of ready and sure inspec- 

 tion, — let us say in a fish from 2j to 4 inches in length, we shall find 

 that whatever be the species examined, the dentition is the same. It 

 consists of 



Upper jaw. — Maxillary teeth , * . . . 19 + 19 = 38 



Intermaxillary do. . . . . 9+9=18 



Palatal 15 + 16 = 31 



Vomerine (anterior group or transverse 



mesial and posterior in a double row) . . . 16 



Lower jaw. — Mandibular 18 + 18 = 36 



Tongue. — Lingual * . . . * * 5+5 = 10 



Thus, as regards the dentition, the young of the Salmonidae is of no 

 species, but a generic animal, whose nearest approach as to type in 

 the adult animal is the common river trout. It possesses all the 

 teeth which any species of the natural family ever has, and more than 

 any adult of any other species, and even in this respect is the perfect 

 animal, i.e. perfect generically. By growth, which means merely the 

 metamorphoses or transformations it has to undergo before acquiring 

 its speciality, the generic young of the Salmonidae simply loses cer- 

 tain teeth, which are not replaced ; it does not acquire any new ones 

 not already existing. As the changes are most remarkable in the 

 system of the vomerine teeth, I shall confine my remarks to these. 



1st. If the young fish is to grow up a river trout simply, it retains, 

 as seems to me, in some species at least, all its vomerine teeth to its 

 adult condition. I have examined large river trout of England, and 

 such I have found to be the arrangement : the transverse or anterior 

 cluster of vomerine teeth, which M. Valenciennes assumes to be 

 absent in the adult of all trout, are quite as distinct and as large as 

 those on the body of the vomer. Here is the dentition as regards the 

 vomerine teeth of a Kennett trout (Hampshire) caught in the waters 

 of Popham, weighing 9f lbs.; the anterior cluster of vomerine teeth are 

 large and distinct; they are five in number; they are followed by a 

 double row of teeth on the body of the vomer, also quite distinct ; 



