430 FOSSIL FISH. 



3. Squalus tricuspidens. We may very probably distinguish 

 from the preceding, and regard as belonging to a species of 

 Squalus not yet known, certain teeth with three points^ but 

 which are straight and very high^ or very slender. They come 

 from the neighbourhood of Brussels, and are figured by 

 Bartin. 



4. Squalus vacca, columbinus, or grineus. A kind of teeth 

 are found in Sicily, with a very broad basis, almost straight, 

 and the trenchant edge of which presents a point, not much 

 raised, not denticulated, compressed, a little curved behind, 

 and accompanied with five or six very strong points decreasing 

 backwards, and three or four much smaller ones in front. 

 They belong, indubitably, to the species called by the Sicilians 

 Squalus vacca. 



The other species of Squali, to which the fossil teeth are 

 referred, are Sq. pristodontus, Sq. lamia, Sq. auriculatuSy De 

 Blain., Q.nd pristobatys dubius? 



There are also found pretty frequently, in the bosom of the 

 earth, in localities, and, as it would seem, in strata of different 

 kinds, the teeth of aetohates^ or raia aquila, separated or 

 united, in greater or less numbers. 



These teeth are sorts of parallelopipeds, of forms a little dif- 

 ferent — sometimes entirely straight, sometimes curved in a 

 chevron form, or thus \S\^\ one of the faces of which is smooth, 

 and more or less hard and varnished, and the other, which was 

 adherent to the skin of the mouth in the living animal, is tra- 

 versed by lines, parallel and perpendicular to the length of the 

 dentary bone. 



It is also to these sorts of teeth, to which the name mylio- 

 dontes may be given, that certain little lozenges or cubes 

 belong, whose structure is the same, but which are much 

 smaller. 



All these pieces, united in greater or less quantity, form a 

 broad plate, usually elongated from front to back, and which 

 is adherent to the skin of the palate and of the place of the 



