242 On tlie Dentition cf t/ie Characinoid Genus Piabuca. 



lias been reproduced in the ' (*ainbridge Natural History,' 

 1904 (vol. vii. ]^. 577), under the enoneous name of 

 "Piahucina'^ ar<jentina. Needless to say, the gcMuis Piahuclna 

 is distinct tVoni the genus Piabuca, and, moreover, contains 

 no species ^^ argentina^ The text does not in any way 

 correct these errors in the plate, since by an oversiglit the 

 name Piabuca is omitted from Bjulenger's provisional scheme 

 of classification of the Characinidpe which immediately 

 j^recedes the figure. It should be referred, as Mr. Boulenger 

 agrees, to group B, the Ilydrocyonina?. 



It m:iy l)c added that the above statement does not exhaust 

 the eriors of the plate referred to, inasmuch as the lettering- 

 is responsible for the transposal of the representations of two 

 other Characinids, Serrasalmo rhombeus and Chalceus angu- 

 latus. These errors of nomenclature, however, are apart 

 from the main issue under discussion, which is the failure of 

 the figure to represent correctly the dental conditions existing 

 in Piabuca. 



Following MUUer and Troschel, Giinther, in the ' Catalogue 

 of Fishes,' 1864 (vol. v. pp. 280 and 343), in part characterizes 

 and differentiates the genus Piabuca by the possession ot 

 uniserial teeth. 



Other authorities make no reference to the serial arrange- 

 ment of the teeth. 



(b) The Maxillary Teeth. — Of the nine teeth (on each 

 side) in the main series of the upper jaw seven are situated 

 in the premaxilla, whilst the last two are in the maxilla. 

 The arrangement is shown in fig. 2 of the illustration. 

 Nevertheless, although the condition is perfectly clear and 

 unmistakable in the prepared skull, it has not, I believe, 

 hitherto been recognized, and such observations as have been 

 recorded are incorrect. 



Miiller and Troschel * make use of the cliaracter in their ^ 



artificial scheme of classification of the Characinidje, according m 



to which Piabuca is to be associated with Cttharinus, Hydro- 

 cyan, Coenotropus (Chilodus), Anostomus [Schizodon), and 

 Leporinus, on the one hand, and dissociated from Gastro- 

 pelecus, Anacyrtus (^Epicyrtus), and Cynodon {Raphiodon), on 

 the other, on the very ground of the presence in it of teeth in 

 the premaxilla and their absence in the maxilla. 



Giinther t, in his synopsis of the genera of the Chara- 

 cinidae and in his description of the genus Piabuca, has fallen 

 similarly into error. 



* ' Horae Ichthyologicte,' p. 24. 



t ' Catalogue of Fishes,' pp. 278-280 and pp. 343-344. 



I 



