266 CETACEA 
of the secretions of the second, or true digestive compartment 
(c). This, which is much smaller than the first, has very thick 
walls, the mucous membrane being filled with numerous tubular 
glands. The surface of this membrane is smooth and soft, 
being thrown into numerous folds, which in this genus are arranged 
in a very peculiar and characteristic manner, so as to form a 
series of prominent longitudinal ridges, each of which sends off 
short lateral ridges at right angles to itself, which interdigitate 
with those proceeding from the next longitudinal ridge. The 
remainder of the stomach (d to f) may be compared to the pyloric 
antrum of the stomach of ordinary mammals. It is elongated, 
cylindrical, and intestiniform, with a smooth lining membrane, 
sharply bent upon itself, and terminating in a very small cir- 
cular pyloric aperture (f). In the Porpoise the commence- 
ment of this cavity is constricted off from the remainder, so as to 
form a small globular sac. In most Dolphins (as Tursiops, Globi- 
cephalus, and Grampus) there are two such small sacs of very similar 
size and form, communicating by circular pylorus-like apertures ; 
and in Hyperoddon the whole compartment is divided by a series of 
constrictions into as many as seven separate cavities, which have 
been regarded as distinct stomachs. Immediately beyond the 
pylorus the duodenum has a globular dilatation, as in the camels 
and some other Ungulates, into the lower end of which the biliary 
duct (h) enters. 
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 phocenoides by Cuvier, 
D. melas by Schlegel, forms the type of Gray’s genus Neomeris.+ 
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.’— 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), $3 to $3. Vertebre: C 7, D 13, L 15, C 30; total 65. 
Dorsal fin low, obtusely triangular or rounded. Pectoral fins rather 
1 Zoology of Erebus and Terror, p. 30 (1846). The name is preoccupied by 
Lamarck for a genus of Polyzoa (1816). 
2 Gray, Cat. Cetacea Brit. Mus. p. 106 (1850). 
