DORAS NIGER. 165 



river, entirely black, which possesses a similar sub- 

 stance. They bite the bait readily, and are an 

 annoyance to fishers, in nibbling off the bait from 

 the hooks which are set for better fish: they are 

 sometimes, but seldom, eaten." 



Doras? NIGER, VaJenc; Black Doras. — Ma- 

 cusi, Saurawari ; inhabitants of Esmeralda, Cuiu- 

 cuiu. Schomh. Draicings^ (2). — It is noted on the 

 drawing of this fish, that there is no adipose dorsal 

 fin ; but this may have been overlooked from the 

 peculiar structure, or very small development or 

 plicate form sometimes assumed by this part; in 

 the uncertainty, we introduce it last. 



At the period of the publication of Spix's Fishes 

 of Brazil, M. Agassiz considered the large Doras 

 figured on plate v. as Corydoras cdenfatus, Spix, 

 Doras Humholdtii, Agas., to be distinct from the 

 fish described in the Zool. Researches of Humboldt, 

 by M. Valenciennes, under the name of D. niger, 

 M. Agassiz pointed out what he considered the dis- 

 tinctions : but as the drawing agrees best with the 

 late description of Doras niger in the Histoire Na- 

 turelle des Poissons, we have given it now under 

 that name, without pretending to settle the ques- 

 tion whether one or two species are involved in 

 those referred to above. In our drawing the fish is 

 coloured entirely black, with a blueish lustre on 

 the fins and tail, and having the belly clouded v/ith 

 dull purple and altogether paler; and the whole 

 showing a metallic or bronze lustre. The eye blue. 

 The cirrhi, six in number, are not so long by one- 



