230 



DELPHINID^. 



the characters of genera are not consistent with my observations, for 

 they appear quite as characteristic of the different genera as those 

 of other orders of Mammalia, though they do not present so many 

 different forms. At the same time, it is true that compilers like 

 Lesson, who appear not to have examined a single skull, have made 

 many genera, founded on very slight characters, and brought together 

 species that have very little relation to each other. 



Por the purpose uf more distinctly defining the species, it has been 

 found necessary to divide them into several groups, so as to arrange 

 them ill what appears to be a more natural series, and circumscribe 

 the genera. 



Synopsis or the Geneea. 



A. Head more or less beaked; beak of the sktdl sJender, as long as or longer 



than the brain-cavity; triangle in front of blowers Jiat. Tlie lateral 

 wings of the maxilla expanded, horizontal. Bottle-noses, 



* Beak of skull coinpressed. Symjihysis of Ivwerjaw elongate. 

 Dorsal Jin distinct, 



1. PoNTOPOBiA. Beak of skull high, compressed. Symphysis of lower 



jaw very long. 



2. Steno. Beak of skull rather compressed, higher than broad. Sym- 



physis of lower jaw long. 



** Beak of skull more or less depressed. Symphysis of lower ja^o moderate. 



3. DELPHiNrs. Dorsal distinct, medial. Beak of skull elongate. Tri- 



angle short, rather depressed, convex above. Crown convex. 



4. TuESio. Dorsal distinct, medial. Beak of skull short, depressed. 



Triangle elongate. Crown convex. 



5. LAGENOBHYNCHrs. Dorsal distinct. Beak of skull depressed, ex- 



panded. Crown shelving in front. 



6. Delphinapterus. Dorsal none. 



B. Head rounded in front, scarcely beaked; beak of the skull depressed, 



broad, scarcely so long as the brain-cavity, 



* Lateral icings of the maxilla horizontal, produced over the orbits. 

 Dorsal distinct. Teeth conical. 



7. Obca. Triangle in front of blowers flat or concave. Teeth large, 



acute, permanent. Intermaxillaries moderately wide. Pectoral 

 broad, short. 



8. Pseudorca. Triangleinfront of the blowers flat. Teeth large, acute, 



permanent. Intermaxillaries moderately wide. Pectoral small, 

 ovate. 



9. Geampus. Triangleinfront of blowers swollen, convex. Upper teeth 



early deciduous. Intermaxillaries broad. 



** Lateral icings of the maxilla shelving doicn over the orbit. Triangle 

 in front of the blower convex. 

 t Teeth permanent, compressed, sharp-edged. 



10. Pnoc^NA. Dorsal fin distinct 



11. Neomeris. Dorsal fin none. 



