230 



DELPniNIDiE. 



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 sHght characters, and brought together 

 species that have very little relation to each other. 



For the puri)ose of more distinctly defining the species, it has been 

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

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

 the genera, 



SYNOPSIS OF THE GeNERA. 



A. Head more or less beaked; beak of the skull slender, as long as or longer 



than the brain-cavity ; triangle in front of bhmers fiat. TJie lateral 

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



* £eak of skull cojnpressed. Symphysis of lower jaw elongate. 

 Dorsal fin distinct. 



1. PoNTOPOEiA. 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. Symjyfiysis of lower j\nv moderate. 



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



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



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



Triangle elongate. Crown convex. 



5. Lagenobhynchus. Dorsal distinct. Beak of skull depressed; ex- 



panded. Crown shelving in front. 



6. Delphinapterxjs. Dorsal none. 



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



broad, scarcely so long as the brain-cavity. 



* Lateral wings of the maxilla horizontal, prodticed 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. PsEUDOBCA, Triangle in front of the blowers flat. Teeth large, acute, 



permanent, Intermaxillaries moderately wide. Pectoral small, 

 ovate. 



9. Grampus, Triangle in front of blowers swoUen, convex. Upper teeth 



early deciduous, Intermaxillaries broad, 



** Lateral ivings of the maxilla shelving down over the orbit. Triangle 

 in front of the bloicer convex. 



t Teeth permanent, compressed, sharp-edged. 



10, Piioc^NA, Dorsal fin distinct 



11, NEOMEnis. Dorsal fin none. 



