15G BULLETIN 36, UNITED STATES NATIONAL MUSEUM. 



SOTALIA PALLIDA (Gervais). 

 (Plate 4, li;^s. 1 ami 2.) 



General form similar to tbat of ^S. flnviatiUs. Beak rather longer 

 and less distinctly marked off" from the forehead. Lower jaw extending 

 beyond the upper. Dorsal fin less elevated than in the S.JluviatUis, tri- 

 angular, strongly emarginated behind. Pectoral fins smaller than in S. 

 fluviatUis ; less pointed and more constricted at the base. 



Upper surface of the body, head, dorsal and caudal fins yellowish 

 white. Under surface of body, lower jaw, and pectoral fins, white. 

 (d'Orbigny and Gervais.) 



Teeth ~, small and pointed. Temporal foss;e large and square. 



Measurements of the exterior. — Total length, 105'^'"; greatest girth, 98''"\ 



Measurements of the sl-nll. — Total length, 34"". 



Habitat. — Upper Amazon Eiver; Nauta, Peru (Gervais)- 1 mouth of 

 Rio iS^egro (Natferer). 



SOTALIA FLUVIATILIS (Gorvais). 

 (Plater), fig. L) 



Head swollen; beak distinct, moderately prolonged. Pectoral fins 

 large, oval in outline and pointed. Dorsal fin falcate, a third longer 

 than high. 



Upper i^arts of the body gray, approaching black ; lower jaw and 

 under surface of the body roseate-lilac. The color of the upper parts 

 is extended through the eye in the form of a broad blackish band reach- 

 ing the pectoral fins, which are likewise blackish. Immediately be- 

 hind this band the light color of the lower surfaces rises higher than 

 elsewhere on the sides. (d'Orbigny and Gervais). 



Teeth, f^. 



Measurements of the exterior. — Total length, lOf™; greatest girth. 

 70"". 



Measurements of tlie skull. — Length of beak, 20"" ; length of mandi- 

 ble, 27""; length of tooth-row of the same, 1G.5''"; length of symphysis, 

 5"". 



Ilahitat. — Upper Amazon River. 



2. STENO Gray. 



Rostrum long, narrow, and compressed. Symphysis of mandible 

 long. Pterygoid bones in contact. Postorbital process of frontal slen- 

 der. Teeth large, 20 to 27; crowns rugose. Vertebrje, GG. 



Beak distinctly marked off" from the forehead. Dorsal and pectoral 

 fins falcate. Color black above, white below, with or without dark 

 lonflritudinal bands. 



I 



