SYNOPSIS OF THE SPECIES OF DOLPHINS. 



1. ARTIFICIAL KEY TO THE GENERA, BASED ON EXTERNAL CHARACTERS. 



Head with a beak which is usually distiuctly marked off from the forehead by a cou- 

 strictiou. 



Dorsal fin absent T). Titrnio. 



Dorsal fiu present ; triangular or ovate. 



Beak not distinctly marked off from the forehead 10. ('cplialorhij^clnin. 



Dorsal fin jireseut ; falcate. 



!7. Lagciiorhi/ucltu.i. 

 ?8. Siujmatlas* 

 ?9. Feresa.* 



Beak distinct, elongated. 



Symphysis of mandible long. 



Crowns of teetii rugose 2. Stciio. 



Crowns of teeth smooth 1. Sotalia sps. 



Symphysis of mandible short. 



i 3. Tursiops. 



Sides without longitudinal bands of color < 1. Sotalia ii\\s. 



( 5. rrodelphinus sps. 



Sides with longitudinal bands of color j r,] pi-JddpMnus sps. 



Head without a beak, or with merely an obtuse ridge margining the upper jaw. 

 Crowns of teeth compressed, spade-sLaped. 



Dorsal fm absent 11. Xcomcnfi. 



Dorsal fui present, triangular or slightly falcate 12. Phoavna. 



Teeth conical, nearly or <]uite upright in the jaws. 

 Teeth in upper jaw deciduous; mandibular teeth few, confined to the region of 



the symphysis 14. Grampus. 



Teeth persistent in both jaws. 



Pectoral fins very long and narrow; teeth confined to the anterior half of the 



rostrum 15. G lohivepkalus. 



Pectoral fins broad, ovate ; dorsal fiu very high and prominent (especially in 



the male), size large 17- Orca. 



Pectoral fins moderate, falcate. 



Teeth few and large; color black; size large. Pelagic 1(>. rsendorca. 



Teethsmall; color bluish-gray. Fluviatile 13. Orcella. 



Teeth irregular and implanted obliquely in the jaws. 



Pectoral fins broad, dorsal fin rudimentary; color white... 18. Ddpliinapterus. 



Teeth wanting (J. e., tusks concealed in the female), or present in the form of a 



single, very long, straight, spirally grooved tusk(i.e., righttuskcou- 



cealed in male; rarely both right and left developed). I'J. Moiiodoii. 



* Known only from skulls. 



151 



