59. arius. 139 



I have observed in several species that the bauds of teeth on the 

 palate become relatively larger with age, so that the vomerine teeth, 

 which in young specimens form a, slightly interrupted band, are 

 confluent into one band in others which are more advanced in 

 growth ; in the same way the palatine teeth may be entirely united 

 with those on the vomer, or separated by a narrow interspace. In 

 species which have rudimentary vomerine teeth, these are sometimes 

 entirely lost with age. 



Synopsis of the Species. 



I. The vomerine teeth are present, and form one continuous or but slightly 



interrupted band, which is more or less confluent with the palatine 

 teeth. 



A. Teeth on the palate villiform. 



a. East Indian species : Hexanematichthys, Blkr., p. 139. 



b. South American species : Gmritinya, Blkr. + Sciades, Blkr., 



p. 143. 



c. African species, p. 151. 



B. Teeth on the palate granular, p. 152. 



II. Teeth on the palate in two generally widely separate patches ; some- 



times the vomerine teeth are present, but widely separate into two 

 small groups which may be continuous with the palatine teeth : Arius, 

 Valenc. 



A. Teeth on the palate villiform. 



a. A large interneural shield on the nape : Arius, sp., Blkr., p. 153. 

 h. No large interneural shield on the nape. 



a. African species, p. 154. 



/3. South American species, p. 155. 



y. Pacific species, p. 157. 



8. East Indian species : Hemiarius, Arius, Cephalocassi*. et 

 Netuma, Blkr., p. 158. 



B. Teeth on the palate granular or obtusely conical. 



a. Teeth on the palate in four groups, those of the vomer being 



present : Ariodes, sp., M. & T., p. 163. 



b. Teeth on the palate in two groups : Pseudarius, Blkr. 



a. East Indian species, p. 166. 

 £. American species, p. 171. 

 Appendix : Bayrus venaticus et B. vertaym, p. 174. 



I. The vomerine teeth are present, and form one continuous or but slightly 

 interrupted band, which is more or less confluent with the palatine 

 teeth. 



A. Teeth on the palate villiform. 



a. East Indian species. 



1. Anus thalassinus. 



Deddi jella, Buss. Fish. Corom. pi. 169. 



Bagrus thalassinus, Rupp. N. W. Fische, p. 75. taf. 20. fig. 2. 



bilineatus, Cuv. & Vol. xiv. p. 434. 



