stitutes a compact layer a quarter of an inch thick all round the sides of the gland,
except at the union with the button-shaped splenule, and invests the internal
portion which has the characteristic texture of the spleen.
Liver (PI. XXVII, figs. 12 and 13).—In one old female, this organ, after
thorough preservation in alcohol, measured about 12 inches in transverse and 9 inches
in longitudinal or antero-posterior diameter. As in most of the whale tribe, it is
thick, smooth, and free from lobular divisions. The umbilical cleft is, however,
deepish, defining almost, equal-sized dextral and sinistral moieties. A short shallow
sulcus or merely superficial indentation on the posterior aspect of the left side was
present in this specimen. The vena cava (v. c.) runs along the posterior border.
The hepatic vessels (h.) enter about the middle of the gland, and, they exhibit thick
dense fibrous walls surrounded by what appears as subsidiary vascular tissue, a
partial rete mirabile. -
Ductus communis choledochus.—The liver opens by two orifices into this duct
(Plate XXVII, fig. 9), and the pancreas by a similar number placed immediately
below the openings of the bile canals. One of the hepatic ducts from the left lobe
is situated anterior to that from the right, which is double, immediately before it
enters the common duct. The duct is a great wide canal three-fourths of an inch
in diameter, almost equalling the capacity of some portions of the small intestine
when laid open, but it gradually diminishes in its course of five inches to the
duodenum to a capacity of 0'06 inch at its opening into the intestinal canal. At its
commencement, marked folds pass down from the orifices of the .bile ducts, transverse
to the long axis of the tube, but beyond the pancreatic ducts there is a limited
area in which the folds are oblique. Throughout the rest of the duct the mucous
membrane is thrown into strong wavy transverse folds, and at about its latter half
these are traversed by three or four longitudinal furrows. To the naked eye the
mucous surface is seen to be minutely pitted and transversely grooved, and in some
parts this structure recalls the appearance presented by the mucous membrane of the
gravid uterus of this species. When examined with a hand lens the pits are seen
to be separated from each other by finely membranous septa and the grooves to be
divided into compartments by similar septa. The pits and septa are of most frequent
occurrence in the hollows between and crossing the transverse folds,-but they occasionally
occur on the folds themselves.
A microscopical examination of the walls of this common bile duct (PI. XXXVI,
fig. 16) disclosed a delicate layer of short columnar epithelium covering the free
villous-like surface. Into this opened the mouths of many long branching lobular
glands (<?.), these latter being crammed with large nucleated cells. These glands,
therefore, doubtless furnish a mucous or other secretion to be added to the biliary
and pancreatic fluids. Beneath them, is a thick layer of elastic areolar tissue (<?.),
and again, considerable strata of transverse and oblique, nucleated and unstriped
muscular fibres (m.).
Intestines.—I shall limit my remarks regarding the intestines to pointing out
that the mucous folds of the duodenum do not form marked valvulse conniventes as
I shall have occasion afterwards to show in Flatanista gangelica. In Orcella, the
duodenal folds (PI. XXVII, fig. 10), instead of forming regular lappets running
quite across or around the cavity, have short rugse directed partly longitudinally,
partly obliquely, and partly transversely; and these enclose more or less lozengeshaped
depressions. In this respect Orcella does also not agree with the allied
genus Globicephalus as described by Dr. Murie.
Narial chamber and appurtenances.—In the description of the exterior of the
animal, mention has been made of the crescentic blow-hole. The posterior nares,
it may be observed, present much the same characters as in Flatanista, afterwards
to be fully treated, save that the large arched crypts that occur in the latter genus
are exceedingly small and irregularly distributed in Orcella.
The spiracular sacs of several genera of the Delphinidce have been described
and figured, and their homology discussed by various writers, more particularly by
John Hunter1 and Von Baer2 and Sibson,3 and more recently by Murie.4 The account
and illustrations given of the sacs of Globicephalus melas by the last mentioned
author are borne out in most respects by my examination of those of Orcella brevi-
rostris. On each side of the blow-hole and within is a more or less irregular
flask-shaped thinnish-walled bag, the so-called “ maxillary s a c b e h i n d these are
tortuous narrow canals, as thick as a goose-quill, whose openings are into the common
spiracular cavity, the so-termed “ naso-facial” sacs or passages. Quite at the
bottom of the blow-hole cavity, and resting on the front of the skull, are the
large “premaxillary” bags, directed forwards and overlaid b y the mass of fibrous
tissue and blubber. The resemblances and differences between these accessory
nasal organs and those of the Gangetic Dolphin (Flatanista) shall be treated of
further on.
Fharynx.—Beyond the presence of a wide glandular orifice situated near the
base of the tube of the larynx and its longitudinal folds, the pharynx does not call
for any special description. The gland is racemose and of the same nature as the
glands investing the faucial region, and which are apparently identical with the
secreting crypts opening by pores on the pharynx of Balcenoptera rostrata described
by Carte and Macalister,4 and from which was expelled a quantity of viscid mucus.
Similar glands have also been described by Turner6 in the pharynx of Balcenoptera
sibbaldii and by Murie6 on the fauces of Globicephalus melas. I t is situated internal
to the articulation of the arytenoids with the cricoid cartilage, and its position in
this locality, on the supposition that it is a mucous gland, would seem to indicate
that its special function was to lubricate this portion of the mucous membrane and
so facilitate the movements of the two cartilages of the larynx on each other in the
respiratory act.
1 “ Observations on the structure and economy of W h a le sP h il. Trans. 1787, vol. xvi. p. 335.
3 “ Der nase der Cetaceen,” Isis, 1826, p. 811.
* Phil. Trans. 1848, p. 117.
4 Trans. Zool. Soo. vol. viii. p. 242; Camb. Joum. Anat. and Physiol. 1871, vol. v. p. 123; and Joum. Linn. Soc.
Zool. vol. xi. p. 146.
4 L . c„ p. 232. « L . o.