142 SALMONOIDS. 



In the Prochilodus, however, both these and the bones of the 

 lower jaw are feeble and are imbedded in the thick fleshy lips, to 

 which, and not to the bones themselves, the minute, flexible, 

 incurved, bristle-like teeth, characteristic of the genus, are attached : 

 they are arranged in a single close-set row. 



The superior maxillary bones are edentulous, and are placed 

 backwards, transversely to the angle of the mouth in the subgenera 

 Schizodus, Serrasalmo, Myletes, and Xiphostoma ; but in the true 

 Salmones and other cognate genera, they support a part, and often 

 nearly the whole of the teeth of the upper jaw. 



In the Salmonidse of the River Nile, which belong to the genus 

 Citharina of Cuvier, the maxillary teeth are nearly as fine and as 

 close-set as in the Chcetodonts, but their free extremity is forked. 

 The pharyngeal bones are beset with velutine teeth. 



In the Schizodus, the intermaxillary and premandibular teeth are 

 broad, and of the incisive type of form, with a crenate superior 

 margin. In the Serrasalmo, (PI. 48, fig. 8,) the corresponding teeth 

 preserve the compressed form, but have a sharp apex, a broad base, 

 and trenchant and finely serrate edges ; these lancetted teeth are 

 arranged in a single series both above and below. 



The Myletes is remarkable for the prismatic three-sided figure 

 of its teeth, the working surfaces of which are cuspidated by the 

 production of the angles into sharp points, (PI. 48, fig. 10). There 

 is a single series of tl^tese teeth in each premandibular, and a double 

 row in each large intermaxillary bone ; behind the two median- teeth 

 of the lower jaw there are two simple conical pointed teeth ; similar 

 but much smaller pointed teeth are scattered over the pharyngeal bones. 

 In the ^enus Raphiodon{\) the teeth, as the generic name implies, 

 are long, slender, and extremely sharp-pointed ; they are implanted in 

 the short intermaxillary, the superior maxillary and the premandibular 

 bones; shorter teeth of a similar shape, alternate with the longer ones ; 

 the pair next the symphysis of the lower jaw, exceed all the rest in 

 size. 



The elongated jaws of the species of Xiphostoma are provided 

 with a single row of small, sharp-pointed, slightly-reflexed teeth ; 

 those on the alveolar border of the short superior maxillaries 



(1) pa<pic, acus, aSovg^ dens. 



