88 PERCOIDS. 



The largest and most fully developed teeth of the Siluroids, as 

 those of the Platy stoma, present under the microscope a modification of 

 the reticulo-medullary type of structure, which nearly resembles that 

 of the salmon and the pike : the meshes of the anastomosing me- 

 dullary canals being open, pretty regular, and either subcircular or 

 polygonal. The thin outer crust of the tooth is traversed by minute 

 calcigerous tubes, having the usual direction vertical to the surface. 



CHAPTER V. 



TEETH OF THE CTENOID FISHES. 



34. Although the fishes of the present tribe are of predatory and 

 voracious habits, like the common perch — their type, yet their 

 teeth are never developed to any considerable size, but in all the 

 species are small, numerous, and closely aggregated, resembling the 

 plush or pile of velvet. In the perch, (Perca jluviatilisj, there is a 

 broad band of these teeth ' en velours,' on each of the interraaxillaries 

 and premandibulars, a narrow band on each palatine, and across the 

 fore part of the vomer ; a small patch of similar teeth is also present 

 on the anterior extremity of each external pterygoid, or transverse 

 bone, which is a rare locality for teeth. There is a series of small 

 plates armed with similar villiform teeth along the concave surface 

 of each of the branchial arches ; and the exposed surfaces of 

 the upper and lower pharyngeal bones are entirely covered with 

 them. The points of these minute denticles are all turned towards 

 the gullet ; and thus, although none of the teeth are sufficiently 

 developed to kill by piercing or laceration, they all combine to hold, 

 to crush and to aid in the deglutition of a living prey. 



In the genus Labrax, besides the localities above mentioned, the 

 tongue is covered with villous teeth. 



In the Etelis, there is a row of moderately long, recurved, conical 



en crochet, et suspendues chacune par un pedicule flexible, dentition dont il n'y a point d'autre 

 example connu." — Cuvier, Reyne Anim, ii, p. 204^ 



