An allied species, differing mainly in the absence of dorsal fin, and in the teeth (with the same form of crown) being fewer in number and of larger size, called _Delphinus phacænoides_ by Cuvier, _D. melas_ by Schlegel, forms the type of Gray’s genus _Neomeris_.[158] It is rather smaller than the Common Porpoise, and almost entirely black in colour. Common off the coast of Bombay, it has been met with in other parts of the Indian Ocean, and near Japan. The British Museum recently received a specimen taken in the Chinese river Yang-tse-kiang nearly a thousand miles from the sea, which only differs from others from India in wanting a patch of small horny tubercles on the back. As such tubercles are present or absent in otherwise similar individuals of _P. communis_, it is doubtful whether they can be regarded as constituting a specific character. _Cephalorhynchus._[159]—Rostrum as long and sometimes slightly longer than the cranial portion of the skull. Pterygoids widely separated from one another. Teeth small (less than 3 mm. in diameter), ²⁵⁄₂₅ to ³⁰⁄₃₀. Vertebræ: C 7, D 13, L 15, C 30; total 65. Dorsal fin low, obtusely triangular or rounded. Pectoral fins rather small, narrow, and ovate. Typified by _C. heavisidei_, from the southern seas. _C. eutropia_ is a very distinct form from the same seas, known only by the skull, and referred provisionally to this genus. _Orcella._[160]—Teeth ¹²⁄₁₂ to ¹⁴⁄₁₄, small, conical, pointed, rather closely set, and occupying nearly the whole length of the rostrum. Skull subglobular, high. Rostrum nearly equal in length to the cranial portion of the skull, tapering. Pterygoids widely separated from one another. Manus of moderate size, not elongated, but somewhat pointed. All the bones of the digits broader than long, except the proximal phalanges of the index and third fingers. Dorsal fin rather small, placed behind the middle of the body. Two species, both of small size—_O. brevirostris_, from the Bay of Bengal, and _O. fluminalis_, from the Irawadi river, from 300 to 900 miles from the sea. Our present knowledge of the anatomy, geographical distribution, and habits of these interesting Cetaceans is almost entirely due to the researches of Dr. J. Anderson.[161]