Inhab. North Pacific (_Capt. Delville, R.N._). Skull, from the Zoological Society’s collection. Family 14. BELUGIDÆ. Beluginæ, _Flower_, _Trans. Zool. Soc._ vi. p. 115. Head rounded in front. Teeth in both jaws more or less early deciduous, rarely wanting or, rather, not developed. Back without any dorsal fin. Pectoral fin small, ovate. Skull with the lateral expansion of the maxilla over the orbit, and the side of the beak, shelving downwards. Fingers short; index and middle fingers nearly the same length, the rest rather shorter; phalanges 2, 5, 6, 4, 3. Cervical vertebræ generally free; the second with a large dorsal process. “The Narwhal and the _Beluga_ appear to separate themselves from all the rest, by certain well-marked structural conditions, especially the characters of the cervical vertebræ. As these two animals are in almost every part of their skeleton nearly identical, even to the number of the vertebræ and phalanges, I am disposed to look upon the exceptional dentition of the former as an aberration of secondary importance, and to unite the two genera into a distinct subfamily, placing it next to the Platanistidæ.”—_Flower_, _l. c._ p. 114. 1. BELUGA. Beluga, _Gray_, _Cat. S. & W._ pp. 231, 306, 393; _Synops. Whales & Dolph._ p. 9. Lateral wing of the maxilla over the orbit shelving downward. Teeth conical in both jaws, early deciduous. Male without any spiral horn-like tooth. Fingers short. Metacarpal bones surrounded with cartilage. Bladebone with large coracoid and acromion processes. Second cervical vertebra with a large dorsal process. Vertebræ 50:—C. 7. D. 10. L. and C. 33. 1. Beluga catodon. B.M. Beluga catodon, _Gray_, _l. c._ p. 307, fig. 61; _Synops. Whales & Dolph._ p. 9, tab. 29. f. 3 (tongue). Delphinus canadensis, _Gray_, _Synops. Whales & Dolph._ t. 5 (head false, with beak). Beluga albicans, _Gervais_, _Ostéogr. Cét._ t. 44. f. 1-5. Delphinapterus, _Lucas_, _Vidensk. Selsk. Skr._ Række 5, Band ix. tab. 8 (skull and teeth, showing how they are worn). Inhab. North Sea, mouths of rivers. 1. Beluga rhinodon, _Cope_, _Proc. Acad. Nat. Sci. Philad._ 1865, p. 5, 1869, p. 13, fig. 1. Inhab. Arctic seas. 2. Beluga declivis, _Cope_, _Proc. Acad. Nat. Sci. Philad._ 1865, p. 5, 1869, p. 14. Inhab. Arctic seas. 3. Beluga angustata, _Cope_, _Proc. Acad. Nat. Sci. Philad._ 1869, p. 20, figs. 2 & 3. Beluga concreta, _Cope_, _Proc. Acad. Nat. Sci. Philad._ 1865, p. 5. Inhab. Arctic seas. These are probably varieties of _B. catodon_, showing that the attachment of the cervical vertebræ, the number of ribs, and the form of the acromion are liable to vary. 4. Beluga canadensis, _Wyman_, _Proc. Bost. Soc. Nat. Hist._ 1865. Inhab. Canada. I believe it to be the same as the former. 2. Beluga Kingii.