42 
MR. C. S. TOMES ON THE STRUCTURE AND 
elastic hinge upon the inner sides of their bases, and are free on the outer side. 
They admit therefore of being bent inwards into the mouth, but they cannot be 
displaced outwards, and so soon as pressure is removed from them, they spring 
back into the upright position. 
In the Lophius the outer row of (anchylosed) teeth in the lower jaw are insignificant 
in size as compared with the large hinged teeth, but in the Hake the disparity is not 
so great. The inner row in the latter fish are however much longer than the outer 
row and stand higher, and it is easy to see the benefit which a fish of its voracious 
habits, feeding amidst shoals of herrings, would derive from the mobility and 
elasticity of its longer teeth. In the dashes which it makes at its prey, if the latter 
were struck by fixed immovable teeth, either the herring would be thrown out of the 
way or the teeth broken ; but with the elastic hinge with which they are furnished 
they would give way, the herring enter the mouth of the Hake, and the teeth 
resume their upright position. 
However, not only are they movable, but they are in several ways modified so as 
to adapt them to this unusual condition. In fig. 26, Plate 4, one of these teeth is 
shown in a section transverse to the jaw ; at the inner side its base is prolonged far 
below the outer side, and terminates in a thin edge, the elastic ligament being attached 
to this edge and to the outer surface of the tooth for some distance up its side, 
embracing rather less than half the periphery of the tooth. 
The ligament is composed chiefly of waved fibres of elastic tissue, and returns the 
tooth to its upright position instantly when the pressure by which it was bent down is 
taken off. It is attached to a rugged surface of bone below, its surface of attachment 
upon the bone being much larger than that upon the tooth, so that it is somewhat 
fan-shaped, and it is perforated to give passage to the nutrient vessels of the pulp. 
The tooth, as will be evident from an inspection of fig. 26, is sufficiently firm under 
a vertical pressure to make it serviceable as a piercing instrument, whilst it at once yields 
to an inward pressure. 
The opposite or outer side of the base of the tooth is quite free, and in no way 
bound down to the bone beneath it, and instead of terminating in a thin edge, it is 
much thickened (see d' in fig. 26), especially on its internal aspect, so that it encroaches 
upon the pulp cavity of the tooth. 
This thickened strengthened portion of the base of the tooth is received upon a 
sort of buttress of bone, which is built up to receive it, and the tooth abuts directly 
upon the bone, nothing in the way of a cushion being interposed. An inspection of 
the figure (fig. 26) will show at a glance that it would be impossible, without tearing 
or greatly stretching the ligaments, to bend the tooth outwards, whilst there is nothing 
beyond the elasticity of the ligament to prevent its bending inwards towards the 
mouth. 
I had always wondered what became of the pulps of the movable teeth of the 
Lophius when its teeth were bent down, and had imagined it to be probable that the 
