216 dr. j. e. gray on the skulls of dolphins. [may 8, 



Lagenorhynchus. 



The skulls of the species in the British Museum may he thus ar- 

 ranged : — 



I. The beak of the skull very flat above, with the edges in front of 



the notches bent up. Teeth-line stojipiny considerably short of 

 the notch. Electra. 



•j- Beak of the skull rather longer (about one-third) than the length 

 of the brain-case. Teeth moderate, four in an inch, those in 

 the lower jaw rather larger. 



1 . Lagenorhynchus electra. Beak rounded in front (Zool. 

 E. & T. t. 13). 



3. Lagenorhynchus asia. Beak attenuated, acute in front 

 (Zool. E. & T. t. 14). 



» 



4. Lagenorhynchus acutus, according to Schlegel's figure of 

 the skull, should be arranged in this section. 



ff Beak of the skull rather shorter than the length of the brain- 

 cavity. Teeth small, Jive or six in an inch. 



5. Lagenorhynchus clanculus. Beak of the skull broad 

 behind, once and three-fourths the width of the notch in length. 

 Teeth five in an inch. 



7. Lagenorhynchus thicolea. Beak of the skull narrow 

 behind, twice as long as the width at the notch. Teeth small, six 



an inch. 



II. Beak of the skull rather flat above and elongate, bent up on the 



edge in front of the notch. Teeth-line reaching nearly to the 

 notch. 



* Beak of the skull narrow behind, as long as or slightly longer than 

 the length of the brain-case. Teeth small, five in an inch. 

 First and second cervical vertebra united by their bodies; third 

 and fourth by the sjjinous processes. Leucopleurus. 



9. Lagenorhynchus leucopleurus. Beak of the skull twice 

 as long as the width at the notch. Teeth small, five in an inch. 



** Beak of the skull broad behind, rather shorter than the length 

 of the brain-case. Teeth large, three in an inch. First and 

 second cervical verlebrce united by their bodies; the third, 

 fourth, fifth, six, and seventh free. Lagenorhynchus. 



8. Lagenorhynchus alhirostris. The beak of the skull once 

 and one-half as long as the width at the notch. 



