148 CYPRINOIDS. 



the five outer ones are the largest and have the triturating surface 

 very elegantly dentated. 



The bream (Brama) has five pharyngeal teeth in a single row on 

 each side ; they are moderately large, compressed and obliquely 

 bevelled to a cutting edge, which works against the occipital tooth 

 above. The teeth of the tench [Tinea) are similar to, but relatively 

 broader than those of the bream : their oblique triturating surface 

 is produced internally into a slightly hooked point, as represented 

 in PL 57, fig. 5 ; they are arranged in a single row, four or five on 

 each side of the pharynx, and work against a thick and dense tri- 

 angular superior pharyngeal plate (a) imbedded in the basi-occipital 

 bone. Similar pharyngeal teeth have been found to characterize two 

 extinct species of tench, viz. Tinea leptosoma and mieropygoptera, 

 Agass. 



Both the tench and carp combine a large proportion of vegetable 

 matter, derived from aquatic plants, with worms and the larvee of in- 

 sects, for their ordinary food ; but the carp, (Cyprinus Carpio), from 

 the nature of its dentition ought to be the most herbivorous species 

 of the family. In this species, the pharyngeal teeth are arranged in 

 two or three rows ; the innermost represented by a single tooth, the 

 second having sometimes two teeth of larger size ; and the outer row 

 including three or four, which are the largest and most complicated, 

 especially the middle one. The anterior and inferior tooth of this row 

 has a round crown, with the centre raised into a small point ; the 

 rest are terminated by a flattened grinding surface, sculptured with 

 transverse undulating furrows. These are not very deep, so that 

 they disappear, as shown in PL 57, fig. 6, when the tooth is mo- 

 derately worn down. Fig. 7, exhibits the grinding surface on a 

 tooth recently anchylosed to the pharyngeal bone, and fig. 8 shows 

 the inferior surface of the furrowed crown of an incompletely formed 

 tooth as seen on looking into the wide and open pulp-cavity. The 

 incudeal triangular dental plate, implanted in the occipital bone, is 

 extremely dense, and presents a clear transparent amber-colour in the 

 carp as in the tench ; but its contour is more equilateral in the carp, 

 and the surface which receives the appulse and friction of the pharyn- 

 geal molars is flatter. 



It is sufficiently obvious from an inspection of the powerful 



