142 THE PRACTICAL FISHERMAN. 



often so precisely similar to the surrounding circumstances of its habita- 

 tion, that it is impossible to detect except by shape the difference 

 between the green rush and the Esox lucius. And then the cruel, strong, 

 enormous jaws, with the razor- like fangs ! Whoever has observed the fish 

 seize on its prey, and marked the repeated grips of that remorseless jaw, 

 will not forget the feeling of aversion which thrilled through him as he 

 watched. 



Whilst thus adverting to the teeth of the pike, it may interest the 

 reader if I reproduce the substance of a paper published in the 

 Quarterly Journal of Microscopic Science recently on the hinged forma- 

 tion of certain of the teeth of this fish. The fisherman who may have 

 noticed the celerity with which a large bait is swallowed may have 

 suspected the presence of such fangs. Like the angler-fish (a member 

 of the same family) and the hake, the pike has them very fully developed. 

 The paper referred to is by Mr. Charles A. Tomes, M.A., F.E.S. After 

 remarking on the peculiarity of hinged teeth in the above-named fishes, 

 this gentleman goes on to state that those hinged teeth have certain 

 characters in common ; they are all capable of being bent down by very 

 slight pressure, but in a single direction only ; to force applied in any 

 other direction they are rigidly immovable. This direction, with certain 

 variations to be described, is inwards and backwards towards the 

 gullet, so as to facilitate the ingress and the swallowing of food ; on 

 the removal of the pressure they rebound to their upright position. 



It appears to Mr. Tomes very probable that adequate examination will 

 discover the existence of hinged teeth in many other predatory fish, as 

 it has long been overlooked in fish so common as the hake and the pike ; 

 meanwhile, it is interesting to note the occurrence of an adaptive modifi- 

 cation involving a considerable degree of specialisation occurring in fish 

 so dissimilar in other respects as the angler, the hake and the pike. 



And what is still more significant is the fact that, whilst the result 

 attained is pretty much the same in the three fish selected for comparison, 

 the details of the mechanism by which it is attained differ markedly, 

 especially in the last two. In the angler and in the hake, the teeth 

 which are hinged form the inner and larger of two rows of teeth set 

 upon the margins of the jaws ; their mobility is therefore serviceable in 

 the way of offering no obstacle to the ingress, but opposing the egress of 

 prey. In the mouth of the pike, on the other hand, the marginal teeth 

 are rigidly anchylose, and the hinged teeth situated on the vomerine and 

 palatine bones are useful, not in the catching, but in the swallowing of 

 the prey. 



In the pike the margin of the upper jaw is toothless (with the excep- 

 tion of a few almost rudimentary teeth in front) ; the lower jaw is 



