230 



BEIPHINIII^. 



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 Kttle relation to each other. 



For the purpose 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 oi' the G-enbea. 



A. Head more or less beaked; beak of the skidl slender, as long as or hnger 



than the brain-cavity ; triangle in front of blowers flat. The lateral 

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



* Seak of skuU compressed. Symphyms of lower jaw elongate. 

 Dorsal Jim, distinct. 



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



jaw very long. 



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



physis of lower jaw long. 



** Beak of skull more or less depressed. Symphysis of lower Jaw moderate. 



3. Dblphinus. Dorsal distinct, medial. Beat of skull elongate. Tri- 



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



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



Triangle elongate. Crown convex. 



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



panded. Crown shelving in front. 



6. DELPHiNAPTBBtrs. DoiSal none. 



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



broad, scarcely so long as the brain-cavity. 



* Lateral loings 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. PsETJDOBOA. Triangle in front of the blowers flat. Teeth toge, acute, 



permanent. Intermaxillaries moderately wide. Pectoral email, 

 ovate. 



9. Gbampus. Triangle in front of blowers swollen, convex. Upper teeth 



early deciduous. Intermaxillaries broad. 



* * Lateral wings of the maxilla shelving doum over the orbit. Triangle 



in front of the blower convex. 



t Teeth permanent, compressed, sharp-edged. 



10. PnociBNA. Dorsal fin distinct 



11. Neomebis. Dorsal fln none. 



