1. PONTOPORIA. 231 



ft Teeth early deciduous, conical. Dorsal none. 



12. Beluga. Teeth in both jaws, early deciduous. Male without any 



horn-like tooth, 



13. MoNODON. Teeth very early deciduous. Male with a projecting 



spiral tusk in the upper jaw. 



A. Head more or less beaked ; heak of the skidl slender, as long as or longer 

 than the brain-cavity. The lateral wings of the maxilla expanded, 

 horizontal. Triangle in front of the blowers flat or concave. Delphi- 

 nina. Bottle-noses. 



* Beak of the skull longer than the brain-case, compressed. Symphysis of 

 the lower jaw elongate. Dorsal Jin distinct. 



1. PONTOPORIA. 



Head with a very long, slender beak. Blowhole transverse, on the 

 crown. Dorsal fin high, falcate, central ; pectoral fins rather elon- 

 gate, sublunate. Skull roundish ; beak very long, compressed, with 

 a strong groove on each side above ; side of the maxilla rather ele- 

 vated ; the edges form a ridge on the side of the upper surface of 

 the brain-cavity; eyebrow with a long cylindrical crest; lower jaw 

 compressed, with a deep groove on each side ; symphysis very long. 

 Teeth small, subcylindiical, smooth, rather hooked, acute. 



Pontoporia, Gray, Zool. Ereb. 8f Terror, 46, 1846 ; Cat. Cetac. B. M. 

 1850, 134. 



Stenodelphis, Gervais, D^Orb. Voy. Amer. Merid. 31. t. 23 (not cha- 

 racterized). 



1. Pontoporia Blainvillii. The Pontoporia. 



Skull, with the tubercles behind the blowholes, broad, slightly 

 convex; eyebrows with a strong, longitudinal crest; upper and 

 lower jaw with a deep, well-defined ridge on each side. Teeth |^f , 

 small, conical, hooked, smooth ; symphysis more than half the length 

 of the lower jaw. 



Delphinus Blainvillii, Freminville, Mus. Paris. 



D. Blainvillei, Gervais, Institute, 1842, 170; Bull. Soc. Philom. 1844, 



38 ; Institute, 1844. 

 D. (Stenodelphis) Blainvillei, Gervais Sf D''Orb. Voy. Amer. Merid. 



Mamm. 31. t. 23 (skull) ; Reichb. Cetac. 128. 70. t. 24. f. 78. 

 Pontoporia BlainviUii, Gray, Zool. E. ^ T. 46. t. 29 (skull) ; Cat. 



Cetac. B. M. 134. 



Inhab. Monte Yideo. Skull, Mus. Paris (if. Freminville). 



M. Freminville described the Dolphin belonging to the skull as 

 white, with a black dorsal band, and 4 feet long. 



in. lin. 



Length of skull 12 6 



Length of beak 8 



Length of symphysis 5 9 



Length of teeth-line 5 4 



M. d'Orbigny believes the dolphin he observed near the mouth of 



