PEACTICAL APPLICATION OF SCIENCE. 9 



To return to the dentition of trout and salmon. Whilst the 

 three families of salmones have in the upper jaw maxillary, 

 intermaxillary, palatine and vomerine teeth, and in the lower, 

 jaw mandibular (those in the tongue being called lingual, and 

 these also are present in all the families), yet the vomerine are 

 differently arranged in each. For the common trout the vome- 

 rine teeth are arranged in a double alternating row, and they 

 hold their ground even in the largest, but are generally confined 

 to what anatomists call the body of the vomer, that is, the elon- 

 gated back part of the bone. To this, however, as I have already 

 remarked, some species offer an exception. For the grown sea 

 trout, however (the salmo trutta), the vomerine teeth are 

 arranged in a single row on the body of the bone, whilst a trans- 

 verse row occupies the forepart of the vomer, which French 

 naturalists call chevron. For the true salmon, on the other hand, 

 when fully grown, the double alternating row of teeth formed 

 on the body of the vomer when it was a smolt, and the single 

 row which remained for a time after the double row had dis- 

 appeared, are now themselves reduced to one or two on the fore- 

 part of the body of the bone, the transverse teeth on those of 

 the chevron remaining to the last. 



Thus you may, by putting your finger into the mouth of the 

 fish, tell, without looking at it, whatever be its size, to which of 

 these natural families it belongs ; but this does not apply to the 

 young of these families, for the same dentition prevails in all. 



Now, if every individual of the great family of the salmonida?, 

 including all trout and salmon, could be brought within this 

 law, then, for the first time, I believe, since science began to be 

 cultivated, the natural history system invented by man would 

 be in accordance with Nature's system or plan; and the great 

 formalist, the puffed up "systematic" would swell and strut 

 and point to his achievement, how he had discovered Nature's 

 plan, arranged her works and omitted nothing. But unfor- 

 tunately for him, and his schemes and methods and formulae, 

 Nature never does her work in this way, but fills up all intervals, 

 leaving no void space in her grand scheme. In the course of the 

 present work I shall mention a fish which externally resembles 

 a salmon, but in its vomerine teeth combines the dentition of 



