T.^NIOIDS. 101 



In the Conodon there is a single row of conical teeth in each jaw ; 

 the six anterior ones are longer than the rest. Behind the conical 

 teeth there is a band of villiform teeth. 



In the Otolithes there are two teeth in the upper jaw much 

 larger than the rest. 



The Ancylodons are also characterized by the extreme length of 

 certain of their maxillary teeth. In the Ancylodonjaculidens these teeth 

 are slightly dilated in the middle, and sharp pointed, so as to present 

 a certain resemblance to an arrow, whence the specific name of the 

 fish. There are two rows of these teeth in each intermaxillary bone, 

 and in the anterior part of the interspace of these rows there project 

 two teeth much longer and more curved than the rest. The preman- 

 dibulars are each armed with a single row of arrow-shaped laniaries, 

 of which the three anterior ones and the fifth are the longest. Besides 

 these laniaries the jaws support a narrowband of fine villiform teeth. 

 The tongue is smooth and edentulous. The pharyngeal teeth are 

 villiform, but the middle ones above are stronger than the rest. The 

 Ancylodon brevipinnis has a single row of laniary teeth in each inter- 

 maxillary bone of which the two median or anterior ones are the 

 longest ; in the lower jaw the median teeth are short, and those at 

 the sides are most developed. 



In the Amphyprions, Pomacentrums, and Glyphisodons, there is a 

 single row of small conical or trenchant teeth on each jaw. Those of 

 the lower jaw in the Glyphisodon are slightly notched on the cutting 

 edge. 



In all these genera the teeth, when fully developed, become 

 anchylosed to the substance of the jaws, but are subject to displace- 

 ment by the absorbent process, excited by the pressure of their 

 successors. In the Maigre {Sciana Aquila) the microscopic texture 

 of the teeth corresponds with the third modification, as exemplified 

 in the teeth of the genus Sphyrcsna (PI. 53) . 



TiENIOIDS. 



41. In the Trachypterus Falx, a species of the first genus of the 

 present family in the Cuvierian system, the mouth is transverse, with a 

 vertical aspect and nearly parabolic form. There are six or eight 



