CLASS PISCES. 121 



We can scarcely separate the datnia from these, 

 although they are destitute of palatine teeth, the 

 profile is more rectilinear, and their dorsal fin less 

 emarginated ! . 



Pelates, Cuv. 



Have the same characters as to the operculum, and 

 the interior as the last ; but their teeth are uni- 

 formly even, and their dorsal fin is but little emargi- 

 nated 2 . 



Helotes, Cuv. 



Still very similar, have the dorsal fin strongly emar- 

 ginated, and are particularly distinguishable, by hav- 

 ing the foremost range of teeth trilobate 3 . 



Most of these fish have longitudinal blackish lines 

 in a silvery ground. 



The percoides, with less than six branchial rays, 

 and with two dorsal fins, include only two genera. 



Trichodon, Steller. 

 In which the preoperculum has some strong spines, 



4. Uneatus, Bl. 238. 2. Ther. jyuia, Cuv. Russel, pi. cxxvi. Ther. 

 theraps, Cuv. and Val. iii. 53. and the other species described in our 

 third volume. 



1 Datnia Buchanani, or Coins datnia, Buchanan, pi. ix. f. 29. and 

 Cuv. and Val. iii. 55. Datnia cancellata, ib. p. 144. 



2 Pelates quinque Uneatus, Cuv. and Val. iii. 56. 



3 Helotes scxlineatus, Cuv. and Val. iii. 57. or Eselavc six lignes, 

 Quoy and Gaym. Voy. du Freyc. Zool. 70. 1. 



