356 MICROSCOPIC ANATOMY OF THE TEETH 



position again. The amount of bending down of which these 

 teeth are capable is not very great when compared with 

 such complete forms of hinging as those of the Hake and 

 the Pike, but when the minute teeth are examined under 

 a hand lens and pushed inwards with a needle, they are seen 

 to be considerably depressed and to recover their position 

 immediately upon removal of the pressure, while owing to 

 the shape of the bony pedestal they resist pressure in the 

 opposite direction. 



The amount of movement is quite sufficient, associated 

 with the strong inward curve of the tooth, to make escape 

 very difficult or impossible for any small creatures captured 

 as prey, which would meet with no obstruction in passing 

 over the crowns of the teeth in entering the mouth. We 

 have thus, in Echineis, a stage in the transition from the 

 fixed teeth of the Shark to true hinged teeth, for here there 

 are elastic ligamentous bands in addition to the capsule 

 seen in the Eel, directing the motion of the tooth chiefly in 

 a particular direction, and the shape of the opposed sur- 

 faces, above described, would appear to be of especial value 

 in giving to this form of hinge as free a movement as possible. 



For a further description of the teeth of Echineis, the 

 reader may be referred to the author's original paper (1). 

 Hake. From the foregoing description it is easier to comprehend 



the structure of the more perfectly hinged teeth of the 

 Hake (Merluccius). 



In this fish the outer row of teeth are anchylosed to the 

 jaw (fig. 236), but the inner row are hinged, and the hinging 

 is of a very complete nature, the tooth being able to be bent 

 inwards to an angle of about 45 and to recover its position 

 with a snap. 



In fig. 237, which is a photograph of a ground section 

 of the hinged tooth of the Hake, and in Plate VI the tooth is 

 seen in its partially depressed position. The front portion 

 of the tooth is thickened at its base, and when returned to 

 its place, this thickened portion is received on an elevated 

 pad or buttress of bone. 



In this preparation it was noticed that the tooth was 

 also attached to the inner margin of the bony pedestal. 

 In the published figures of the hinged teeth of the Hake 



