220 



LECTURE IX. 



five, or six sides, Myliohates,fig. 60.* The cone is the most com- 

 mon form in fishes : such teeth may be 

 slender, sharp-pointed, and so minute, 

 numerous, and closely aggregated, as 

 to resemble the plush or pile of velvet; 

 these are called ' villiform teeth (denies 

 viUiformes, dents en velours^) ; all the 

 teeth of the Perch are of this kind : 

 when the teeth are equally fine and 

 Jaws and teeth ; Myiiobates. numerous, but longcr, they are called 



* ciliiform ' (denies ciliiformes) : when the teeth are similar to, but 

 rather stronger than these, they are called 'setiform (deities seii- 

 formes, denis en brosse) : conical teeth, as close set and sharp 

 pointed as the villiform teeth, but of larger size, are called ' rasp- 

 teeth' (denies raduliformes, denis en rape or en cardes) ; the 

 Pike pi'csents such teeth on the back part of the vomer : the teeth 

 of the Sheat-fish (Siluriis glanis) present all the gradations 

 between the villiform and raduliform types. Setiform teeth are com- 

 mon in the fishes thence called Cha3todonts| ; in the genus Citharina 

 they bifurcate at their free extremities ; in the genus Plaiax they end 

 there in three diverging points (V, pi. 1), and the cone here merges 

 into the long and slender cylinder. Sometimes the cone is compressed 

 into a slender trenchant blade : and this maybe pointed and recurved, 

 as in Murcena (V, pi. 5Q,Ji(j. 4.) ; or barbed, as in Trichiums (V, pi. 

 \,fig 8.), and some other Scomberoids ; or it may be bent upon itself, 

 like a tenterhook, as in the fishes thence called Goniodonts.§ In the 

 Bonito may be perceived a progressive thickening of the base of the 

 conical teeth ; and this being combined in other predatory fishes with 

 increased size and recurved direction, they then resemble the laniary 

 or canine teeth of carnivorous quadrupeds, as we see in the large teeth 

 of the Pike. 



The anterior diverging grappling teeth of the wolf-fish (V, pi. 60.) 

 form stronger cones ; and by progressive blunting, flattening, and 

 expansion of the apex, observable in different fishes, the cone by 

 degrees changes to the thick and short cylinder, such as is seen in the 

 back teeth of the wolf-fish (Y, pi. 61.), and in similar grinding and 

 crushing teeth in other genera, whether phytiphagous, or feeders on 

 crustaceous and testaceous animals. The grinding surface of these 

 short cylindrical teeth may be convex, as in the Sheep's-head Fish 

 (Sargus, V, pi. I. fig- 13.) ; or flattened, as in the pharyngeal teeth of 



* See V. pi. 25. 49. 



f The French terms are those used by Cuvier and Valenciennes in xxiii. passim. 



i XaWri, bristle ; o^ovs, tooth. § Twvia, an angle ; oSouy, a tooth. 



