Inia Geoffrensis, D’Orbigny, in Ann. Mus. Paris, vol. iii. p. 23; Gervais, Ostéog. Cét. t. xxxii.
Inhab. Brazil, river Amazon.
“The number of the teeth in the different specimens of Inia examined shows a considerable range of variation, presuming that they all belong to one species. In the one now described there are R. 26, L. 26 / R. 25, L. 27 = 104. The larger specimen in the British Museum, from Ega, has 28-28/26-27 = 109, and also two minute rudimentary teeth in the gum behind the last in the left maxilla. In the smaller skull from the same place there are 29-26/28-27 = 110. In the skull in the Paris Museum, brought by D’Orbigny, there are, according to Gervais, 33-33/33-33 = 132; but in the type specimen in the same museum, taken from Lisbon, the number is given by De Bainville as 26-26/26-26 = 104. In the Berlin skull the teeth are 34-32/33-32 = 131. Von Martius, in his diagnosis of the species, gives 28-28/29-29 = 114.”—Flower.
Family 10. DELPHINIDÆ.
Delphinidæ, Gray, l. c. pp. 228, 393; Synops. Whales & Dolph. p. 4; Flower, Trans. Zool. Soc. vi. p. 113.
Head beaked. Teeth in both jaws, conical or compressed, permanent, without any internal lobe, occupying nearly the whole length of the jaws. Back rounded, with a falcate dorsal fin; rarely absent. Skull with the maxilla expanded over the orbit, and more or less turned up on the edges.
“Costal cartilages firmly ossified. Posterior ribs losing their capitular articulation, and only uniting with the transverse processes of the vertebræ by the tubercle. Anterior (2-6) cervical, in most, ankylosed together. Pterygoid bones short, thin, involuted to form, with a process of the palatine bone, the outer wall of the postpalatine air-sinus. Numerous teeth in both jaws (Monodon excepted), sometimes deciduous. Symphysis of mandible short or moderate, never exceeding one-third the length of the ramus. Bones of the skull not raised into a distinct crest behind the anterior nares. Orbit of moderate size. Lachrymal bones not distinct from the jugal. Pectoral limbs varying much in form and size. Dorsal fin usually present.”—Flower.
Tribe I. STENONINA.
Stenonina, Gray, Synops. Whales & Dolph. p. 5.