82. RHINODORAS. 209 



82. RHINODORAS. 

 Oxydoras, sp., Kner. 

 Oxydoras et Rhinodoras, Bleek. Nederl. Tydschr. Dierk. 1863, p. 84. 



Adipose fin low, rather elongate, gradually passing into the profile 

 of the back ; dorsal fin with a strong spine and with six soft rays ; 

 anal short. Teeth very small, or entirely absent. Cleft of the mouth 

 rather narrow; barbels six, not united at the base. Eyes small. 

 Neck with broad dermal bones ; a large humeral process above the 

 pectoral fin ; a series of shields along the middle of the side of the 

 body and tail, each shield with a compressed, prominent central spine. 

 Gill-openings of moderate width, not extending downwards to the 

 throat. Ventral fins with seven rays, inserted behind the dorsal. 



Rivers of South America flowing into the Atlantic. 



1. Rhinodoras niger. 



Doras niger, Valenc. in Humb. Observ. Zool. ii. p. 184 ; Cuv. fy Vat. xv. 



p. 291. 

 Corydoras edentulus, Spix, Pise. Brasil. tab. 5. 

 Doras humboldti, Ac/ass. in Spix, Pise. Brasil. p. 14. 



D. 1/6. A. 11-12. P. 1/10. V. 7. L. lat. 24-25. 



The adipose fin is a long and low fold. Lateral shields longitudi- 

 nally striated, of moderate size, the middle being about half as high 

 as the body. Humeral process granulated, tapering behind, and 

 extending somewhat beyond the middle of the pectoral spine. The 

 upper and lower surfaces of the tail are not shielded. Eye small, its 

 diameter being one-half of its distance from the posterior nostril. 

 The maxillary barbels extend to the eye, and are thicker but not 

 much longer than those of the mandible, which are not united by a 

 membrane. Teeth none. Blackish olive ; shields yellowish. 



River Amazons. San Erancisco River. 

 a. Adult (13 inches long). River Amazons. Purchased of Mr. Stevens. 



2. Rhinodoras knerii. 



Oxydoras niger, Kner, Sitzgsber. Wien. Acad. 1855, xvii. p. 146 (not 



Valenc.). 

 knerii, Bleek. Nederl. Tydschr. 'Dierk. 1863, p. 14. 



D. 1/6. A. 11-12. L. lat. 34. 

 This species appears to be distinct from Rh. niger, having 34 lateral 

 shields ; otherwise they are very similar to each other. 

 Cujaba. 



3. Rhinodoras orbignyi. 



Oxydoras d'Orbigny (Kroy.), Kner, Sitzgsber. Wien. Acad. 1855, 



p. 149. fig. 9. 

 Doras d'Orbignii, Hyrtl, Denkschr. Acad. Wiss. Wien, 1859, xvi. . 17. 

 Rhinodoras orbignyi, Bleek. Nederl. Tydschr. Dierk. 1863, p. 1 . 



D. 1/6. / A. 12. L. lat. 29. Vert. 10/21. 

 Adipose fin long, rather low, gradually passing into the profile of 

 the back. Lateral shields of moderate height, with the hind margins 



