80. dokas. 205 



besides, the present specimen is considerably larger than the one 



figured. 

 It appears to be extremely doubtful whether the specimens de- 

 scribed by Gronow and Schneider really had a spine in the adipose 

 fin ; and it is very probable that Valenciennes and Kner are right in 

 identifying specimens examined by them, without such a spine, with 

 the species described by the old ichthyologists. 



** Lateral shields less than twenty. 

 11. Doras dorsalis. 

 Doras carinatus, Valenc. in Humb. Observ. Aool. ii. p. 184 (not synon.). 



dorsalis, Cuv. 8f Vul. xv. p. 284 ; Kner, Sitzqsber. Wien. Acad. 



1855, xvii. p. 128. 



D. 1/6. A. 14. P. 1/8. V. 7. L. lat. 16-17. 



The anterior lateral shields kidney-shaped, the posteiior longitu- 

 dinally ovate. The humeral process is short and narrow, extending 

 to the middle of the pectoral spine, and tapering behind. The max- 

 illary barbels reach to the extremity of the humeral spine, and are 

 twice as long as the outer mandibulary barbels. The back between 

 the first dorsal fin and the caudal, and the space between the anal 

 and caudal are shielded, but these shields are sometimes very small ; 

 a shield on each side of the base of the adipose fin. 



Cayenne ; Para Rio. 



12. Doras lithogaster. 



Doras lithogaster (Heck.), Kner, Sitzungsber. Wien. Acad. 1855, xvii. 

 p. 132. 



B. 7. D. 1/6. A. 13. P. 1/8. V. 7. L. lat. 16-17. 



Both jaws with a band of villiform teeth. Barbels not fringed : 

 those of the maxillaries extend scarcely to the operculum, the outer 

 ones of the mandible being one-half shorter than the former, but 

 longer than the inner ones. Eye rather small. The humeral process 

 is short and narrow, terminating in a rounded point, opposite the 

 middle of the pectoral spine. The second lateral shield is the highest, 

 reaching another large one situated along the base of the dorsal fin. 

 A series of shields along the dorsal line, between the dorsal and 

 caudal fins ; another along the lower side of the tail, between ven- 

 tral and caudal fins. All the parts between the series of shields and 

 the sides of the head are covered with more or less scattered small 

 shields. Back clouded with blackish. (Kner.) 



Forte do Rio Branco. 



13. Doras papilionatus. 

 Doras papilionatus, Filippi, in Guer.-Menev. Rev. & Mat/. Zool. 1853, 

 p. 167. 



D. 1/6. A. 12. L. lat. 18. 

 Five shields on the back between the dorsal and adipose fins, the 

 space between the adipose and caudal being naked. (Fil.) 

 River Amazons. 



