The following is a synopsis of tho genera and sub-families of this extensive family :— A. Jaws tapering; the symphysis of the lower jaw short, not half the length of the jaw. Dorsal fin generally distinct ; pectoral fin ovate, acute. Marine.
a. Upper jaw toothless ; lower jaw with only one or two teeth (which are often hidden in the gums) on each aide. Beak of the skull keeled on each side, the keel being sometimes large, and forming a kind of reflexed wing on each side ; head with a short beak. Hyperoodontina.
1. II yperoodon. The beak of the upper jaw with a large erect wing-like expansion in front of the blowers ; lower jaw with two rudimentary teeth In front.
Ziphius. Beak of upper jaw keeled on each side; lower jaw broad, bent down in front with largo compressed teeth In the middle of each side.
3. Delphinorllnehus. Beak of upper jaw keeled on each side ; lower jaw nearly straight, with two or three small rudimentary conical teeth in the middle of each side.
b. Upper and lower jaw with few or deciduous teeth. Wings of the maxillary bones expanded and shelving downwards. The bunk short, deflexed. Forehead convex. Ilead rounded, without any beak. Monoceratina.
• Lower jaw toothless.
4. Monodon. Upper jaw of males with one or two very long projecting spirally-twisted tusks. Dorsal fin none.
•• Upper and lower jaw with conical, early deciduous teeth.
5. Beluga. Dorsal fin none.
••• Upper and lower jaw with compressed permanent teeth. O. Nem/let-ie. Dorsal none.
7. I'hoca•na. Dorsal triangular, in the middle of the back.
c. Upper and lower jaw with many teeth, rarely deciduous with age. Wings of the jaw-bone horizontally produced over the orbits. Delphinina.
• Head rounded in front, not beaked. Nose of skull scarcely so long as the brain-cavity. Dorsal distinct 8. Grampus. Teeth conical, truncated, early deciduous. Inter maxillaries broad. Pectoral ovate.
0. Globiocephalus. Teeth conical, deciduous when old. Inter maxillaries very broad. Pectorals narrow, linear.
10. Orca. Teeth conical, acute, permanent. Iatermaxillaries moderato. Pectorals ovate.
•• Head beaked. Nose of skull as long as or longer than brain-cavity.
11. Lagenorhynehus. Head shelving in front. Dorsal rather
posterior. Nose of skull depressed, expanded.
12. Ddphinapterus. Head rather convex in front. Dorsal none. Nose of skull rather depressed, convex above.
13. Delphinus. Head rather convex in front Dorsal medial. Nose of skull rather depressed, convex above.
14. Steno. Head rather convex in front. Dorsal medial. Nose of skull compressed, higher than broad ; symphysis of lower jaw rather elongate.
15. Penteporia. Head rather convex in front. Dorsal medial. Nose of skull rather compressed ; high symphysis of lower jaw very long.
B. Jaws much compressed ; symphysis of the lower jaw very long. Dorsal none. Teeth in both jaws. Fluviatile.
d. Skull with the maxillary bones simple, expanded over the orbit. Teeth conicaL Paddles ovate or oblong. Iniona.
16. /tam Teeth rugose; the hinder ones with a rounded tubercle oa the inner side.
e. Skull with the maxilliary bones bent up in front of the blow-era, and forming a vault. The teeth compressed. The paddles fan shaped, truncated at the end. Platanistina.
17. Platanista.
Hyperoodon Butzkopf, the Bottle-Head. It is the Flounder's Head of Dale, in his History of Harwich,' where it has been taken. Pennant calls it the Beaked Whale. It inhabits the North Sea.
rostratum, the Beaked Hyperoodon, is an inhabitant of the North Sea. It differs from the last species in having the dorsal fin behind the middle of the back. It has been taken in the Thames and the Humber, and skeletons exist in the museums of Edinburgh, Bristol, and Liverpool.
Two other species of Hyperoodon are described by Dr. J. E. Gray, Desmarestii and IL latifrens. The latter is a native of the North Sea, and has been taken on the coast of Lancashire.
Ziphius Sowerbiensis is the Phyaetcr bidens of Sowerby, the Diodon bidens of Bell. The head of a specimen caught in Scotland is now in the museum at Oxford. Dr. Gray observes that "it belongs to the genus Ziphius of Cuvier, before only known in the fossil state; and the examination of the skull has proved the accuracy of these determinations." Z. Sechellensls, named from a skull in the museum at Paris brought from the Sechellea.