2. STENO. 237 



jaw rather slender and slightly bent nj) at the tips. Symphysis 

 rather keeled beneath in front. 



Steuo Tucuxi, Grai/, Ann. Sf 3Iag. N. H. 1857, xviii. 158. 



Inhab. The upper parts of the Amazons River, near Santarem 

 {Bates). Called Twuxi. 



The males are larger. It does not roll over like the Bouko, but 

 comes to the surface to breathe. 



Male. Female. 

 in. lin. in. lin. 



Length of the skull 13 12 



Length of the beak 7 3 6 6 



Length of teeth-line 6 5 9 



Length of lower jaw 10 3 9 6 



Length of symphysis 2 1 3 



Width of skull 6 5 6 



Width of beak at notch 2 (J 2 3 



Width of forehead over notch 4 9 4 6 



8. Steno ? fluviatilis. 



Above blackish, a broad band from the eye to the pectoral, and 

 the pectoral fin black. Lower jaw and beneath rosy white, the 

 white bent up so as to form a broad white lobe behind the orbit over 

 the pectoral. Teeth |-|- or -H on each side. Dorsal fin moderate, 

 falcate. 



Delphinus fluviatilis, Gervais Sf Delille, Btill. de la Soc. Agric. tie 

 VHerault, 1853, 148; Gervais, in Casteln. Voy. Mamm. 92. t. 19, 

 f. 2 ; Hist. Mamm. ii. 522. 



Buffeo negro, Missionaries of Upper Amazons. 



Bolo preto of the Brazilians, in Casteln. Hist, du Voy. dans FAmer. 

 du Sud, iv. 460, v. 33. 



Inhab. Upper part of the River Amazons, near Peru. Probably 

 the same as the former. 



An imperfect skin with the ends of the beak of the skull in the 

 Paris Museum. The palate of the beak is flat, without any lateral 

 grooves. The teeth are small, acute, and, like those of De^Mnus 

 Delphis, without any internal lobe. 



9. Steno ? pallidus. 



Teeth f|- or |^. Pale yellowish white above, beneath white. 

 Dorsal fin very low. 



Delphinus pallidus, Gervais, Acad. Set. Montp. 1855 ; Casteln. Voy. 

 Mamm. 94. t. 19. f. 1; Ann. 8f Mag. N. H. xvii. 521 ; Bates, Tra- 

 vels in Brazil. 



BuiFeo bianco, Missionaries of Upper A^nazons, Casteln. Hist, du Voy, 

 dans VAmer. du Sud, iv. 460. 



Inhab. River Amazons. May be the same as S. T%ictiAi. 



