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Show 216 DR. J. E. GRAY ON THE SKULLS OF DOLPHINS. [May 8, LAGENORHYNCHUS. The skulls of the species in the British Museum may be thus arranged :- I. The beak of the skull very flat above, with the edges in the notches bent up. Teeth-line stopping considerably short the notch. Electra. + Beak of the skull rather longer (about one-third) than the 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, five 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 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 the length of the brain-case. Teeth small, five in an inch. First and second cervical vertebrar united by their bodies; and fourth by the spinous processes. Leucopleurus. 9. L A G E N O R H Y N C H U S 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 vertebrar united by their bodies; the third, fourth, fifth, six, and seventh free. Lagenorhynchus. 8. L A G E N O R H Y N C H U S ALBIROSTRIS. The beak of the skull once and one-half as long as the width at the notch. |