Vertebræ 41. C. 7. D. 13. L. 3. C. 18. The smallest number of any Cetacean known.
“Costal cartilages not ossified. The tubercular and capitular articulations of the ribs blending together posteriorly. Cervical vertebræ all free. Pterygoid bones thin, not conforming in their mode of arrangement with either of the other sections. Jaws very long and narrow, both with numerous teeth having compressed fangs. Symphysis of mandible very long, exceeding half the length of the entire ramus. Orbit very small. Lachrymal bones not distinct from the jugal. Pectoral limbs large. Dorsal fin rudimentary.”—Flower.
“Maxillary crests absent, or very slightly developed. Many of the teeth with a complete cingulum or a distinct tubercle at the base of the crown. Pectoral fin ovate, obtusely pointed.”—Flower.
1. INIA.
Inia, Gray, l. c. p. 226; Synops. Whales & Dolph. p. 4; Flower, Trans. Zool. Soc. vi. p. 87.
Cervical vertebræ free: the first with an inferior posterior process, bifid at the end; lateral processes very short: the second with a strong dorsal process. Dorsal vertebræ with very high dorsal processes. Scapula very high, with very long acromion and coracoid processes. The arm-bone short. Forearms thick and short, scarcely so long as the upper arm-bone. Metacarpal bones seven, imbedded in cartilage. The second and third fingers very long, with six phalanges; the first finger very short, of two phalanges; the fourth strong, short, about as long as the first two phalanges of the third finger, of four phalanges; the fifth finger very short, slender, of three phalanges. The breast-bone ovate, scutate, notched in front.
1. Inia Geoffroyii.
Inia Geoffroyii, Gray, l. c. pp. 226, 393; Synops. Whales & Dolph. p. 4; Flower, Trans. Zool. Soc. vi. p. 87, t. 25, 26, 27 (skeleton).
Delphinus amazonicus, Spix, Reise in Brasil. t. iii. pp. 1119 and 1113, fig. 34 (bad).