15(3 BULLETIN 36, UNITED* STATES NATIONAL MUSEUM. 



SOTALIA PALLIDA (Gervais). 

 (Plate 4, fij^s. 1 iuul2.) 



General form similar to tbat of >S'. fluviatllis. 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.fliiviatilis, tri- 

 angnlar, strongly emarginated behind. Pectoral fins smaller than in 8. 

 Jluviatilis ; less pointed and more constricted at the base. 



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

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

 (d'Orbigny and Gervais.) 



Teeth "j^, small and pointed. Temporal fossse large and square. 



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



Measurements of the slcull. — Total length, 34*''". 



Habitat. — Upper Amazon Eiver; Nauta, Peru {Gerva,is)- ? mouth of 

 Eio Negro {Natterer). 



SOTALIA FLUVIATILIS (Gorvais). 

 (P]ato5, fio-. 1.) 



Head swollen; beak distinct, moderately prolonged. Pectoral fins 

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

 than high. 



Upper parts 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 i^ectoral 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, II. 



Measurements of the exterior. — Total length, 101''"'; greatest girth, 

 70'">. 



Measurements of the sl-ull. — Length of beak, 20*^™; length of mandi- 

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

 5"". 



Habitat. — Upper Amazon Eiver. 



2. STENO Gray. 



Rostrum long, narrow, and compressed. Sym^ihysis of mandible 

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

 der. Teeth large, 20 to 27; crowns rugose. Verteb rie, 6G. 



Beak distinctly marked off from the forehead. Dorsal and i)ectoral 

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

 longitudinal bands. 



