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[ 127 ] Le F. Dice

V. On the Form and Structure of the Manatee (Manatus americanus).
By Dr. James Murin, /.L.S., F.GS., &e.

Read November 15th, 1870.
[Puates XVII. to XXVI.]

I. Exterior ASPECTS AND DIMENSIONS.

1. GENERAL CONTOUR.—Awmong original investigators of the uncouth aquatic
mammal the Manatee, the painstaking Daubenton, in one of Buffon’s well-known
volumes, has given a representation of a foetus in profile, and of the head foreshortened’.
These evince only a certain accuracy, being too small to bring out the minor tegu-
mentary characters. This remark applies in common to Sir Everard Home’s better
executed figure*, copied by Frederick Cuvier*, to J. A. Albers’s foetus’, and to that of
Alexander von Humboldt’. Dr. Hermann Stannius® in his larger illustrations of the
head of the animal, likewise fails to depict skin-texture, although the peculiarities
of the muzzle are effectively rendered. Professor W. Vrolik’ expresses himself thus
concerning his own folio plates:—‘“I suppose that my representation is quite exact,
and will give such a just idea of the animal that it is useless to enter into more
particulars.”

It is therefore in no hypercritical or self-satisfied spirit that I draw attention to
pictorial defects in the able treatises of these revered preceptors of comparative
anatomy, but rather in vindication of my reproducing work already done. Of the two
specimens which have come under my scalpel, female and male, I was content to
note that the former did not coincide in certain points with Vrolik’s delineation.
Bethinking myself, however, on receipt of the latter, that a good photograph would be
a desirable acquisition, I took such views as seemed best to afford evidence of the
external affinities of this singular creature, and of the adaptability of its unwieldy
carcass to propulsion through a watery element. In museums, it is customary to see

* Histoire Naturelle, tome xiii. plate 57. ? Lectures on Comp. Anat. vol. iy. pl. 55.

3 Pl. 1 of the Hist. Nat. des Cétacés. Paris, 1836.

Icones ad illustrandam Anat. Comp. fase. ii. tab. iv. Lipsiz, 1818.

5 In Dr. Wiegmann’s ‘ Archiy fiir Naturgeschichte,’ 1838, p. 1, pls. 1 & 2.

Beitrage zur Kenntniss der amerikanischen Manatis von Hermann Stannius. Rostock, 1846. Tab. 1.
figs. 1 & 2,

7 « Bijdrage tot de Natuur- en Ontleedkundige Kennis van den Manatus americanus,” p. 58 (pls. 1 & 2), in
the Memoirs of the Zool. Soc. Amsterdam, Natura Artis Magistra, 1852. For a copy of this folio monograph
I am indebted to the liberality of J. Norrdhoem Heyt, Superintendent of the Zoological Gardens, Amsterdam.

VOL. VIII.—PART 11. September, 1872. x

128 DR. J. MURIE. ON THE FORM AND STRUCTURE OF THE MANATEE.

such bloated over-stuffed specimens, that from them, as well as figures extant, an unfair
idea of the configuration is obtained, and one is embarrassed to comprehend the mode
of progression of such an awkward form in water as on land.

Emendations on the text of the forementioned authors relative to the shape of the
animal are less necessary; so that I limit myself to a notice of the points which photo-
tography has elucidated in the present case. Pl. XVII. fig. 1, profile view, shows that
in the young Manatee the head and body, to as far as the root of the tail, have together
a very elongated biconical contour—not so protuberant at the posterior belly part as in
Home’s figure, and quite different from the barrel-like aspect of Vrolik’s animal. Seen
on the dorsal (Pl. XVIII. fig. 5) and on the ventral (Pl. XVII. fig. 2) aspects, the biconical
form is less rigid, from the deep skin-sulci being more emarginate ; whilst towards the
pelvic region there is a sudden rugged contraction, as if behind the ribs a broad band
had been tightly lashed round the short axis of the body. Posteriorly to this the outer
border-lines obliquely diverge in a very gradual and regular manner, so as to form a
comparatively long and very broad, thin, shovel-shaped, caudal organ.

The hindermost border, whilst rounded’, has a remarkable truncated character, and
centrally is incised; or rather there is a short, shallow longitudinal sulcus on its upper
surface, which forms a corresponding convexity below. ‘The tail of Home’s specimen
gives a three-quarter or tilted view; but this, if compared with the present fig. 1, is too
much narrowed at the end. ‘The Beaver-shaped tail attributed to Manatus by some
writers is true only to a certain extent, inasmuch as in the latter it broadens greatly
compared with the former, and, as Albers’s figure distinctly represents, there is a slight
mesial V-shaped indentation or emargination.

Regarding the head, Stannius’s figure is by far the most trustworthy; but, as already
particularized, the absence of texture detracts from the otherwise characteristic phy-
siognomy of the creature. W. Vrolik’s best representation, to my mind, seems to be
that depicting the under surface of the lower jaw and muzzle (pl. 2. fig. 5); his front
foreshortened view of the head (pl. 2. fig. 4) has far too large, staring eyes; and these
are not widely enough apart. The facial expression, as dependent on the eye, is
markedly noticeable on comparing Vrolik’s plates and those now given. The accuracy
of the present lithographs are vouched for as carefully taken photographs, faithfully
and minutely copied by my artists, Messrs. Berjeau and Smit, figure 3 alone having
been slightly reduced from the negative impression so as to fit the length of the plate.

2. Admeasurements—Humboldt, Stannius, and Vrolik have each recorded some of
the proportional dimensions of the body. On this account it might be deemed super-
fluous to institute a fresh series of measurements, were it not that it lends precision to
the description and figures of the specimens under immediate consideration. Inches
and decimals have been taken as the standard throughout.

1 This peculiarity has evidently caused the adoption of the name “ Round-tailed Trichechus” for the
Manatee, vid. Shaw’s ‘ Zoology,’ vol. i. p. 244.

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

Female.
Body generally. inches,
Extreme length, from the snout to the tip of the tail . . 65:0
Girth of neck just behind vertex of cranium ; —
Girth immediately in front of the pectoral extremities . . 32:5
Girth immediately behind the pectoral extremities . 39°
Girth about 43 inches in front of the umbilicus . . . . 47-0
Cuathy abi she Gun DINOS. oe co is Gu kiols Osi 26 go. sabl-O
Girth at the opening of the penis in the male . ; —
Girth at about 3 inches in advance of rectum in male, or
equivalent to the position of the vulva in female . . . 41-0
SiG eg AUS 8 a6 da diet Li Sein dwtosugeniig Aec8e'd
The Head.
Extreme length, or distance between the muzzle and occiput 11:3
Girth at the snout, including the lower lip. . . . . . 140
Girth vertically before the eyes, including the lower lip: 18-6
Girth behind the projecting part of lower lip, vertical to
TCAD i acy eau Maik sth ety B . 20:0
Girth, middle of head, just anterior to projection of mandible 23-0
Oral region, or length of side of the mouth 2°2
Length of under lip, following tegumentary curve 4-5
Breadth of chin, following tegumentary curve . 4-()
Breadth of chin at the angles of the mouth. 5:0
Muzzle and Nostrils.
Measurement of arch over muzzle covering nostril 8-5

Nasal orifices, distance behind free end of muzzle.
Nasal orifices, diameters across and vertically, when dilated,
about Sra etelo.dd bite a ene Be

Nasal orifices, distance apart at inner angles, about
Nasal orifices, distance apart at outer angles

The Eye.
Diameter . ne COOP: OTT Ree
Distance from front of muzzle (outside) .
Distance from front of muzzle (mesially)
Distance from the inner angle of nostril .
Distance between them at their centres .
Distant from the angle of the mouth .

The Ear.
Auditory orifice distant from posterior angle of eye .
Auditory orifices apart from each other in diameter .

xen

Male.
inches.
48-0
24°5
25°5
28°5
29°5
31:5
52°5

28-0
20-0

9:0
12:5
15:0

17-0
20°5

1

9

a

9

130 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

Female. Male.

Pectoral Extremity. inches. inches.
Distant fromthe muzzle:i) io uitalh diese a) deel pie 10-0
Distant from the end of tail. . . . . oo 38°0
Width from one tip to the other when ofatimotehibaul oo 25°0
Roots apart from each other, following curve of back . . 19:0 —
Extreme length of free portion i) 05 '.29).0 6 eet. 8, 200 8-0
Extreme breadth of free portion ... «) w+ .eo~ se 3°5
At the narrowest portion its transverse diameter is . . . — 2°5
Girth at the root . . Leb A HEL A, Sethe», da: 8-0
Girth at about the tail Ati duels CUT logtiyy gies = LORS 8:0
Girth at about the outer or distal chiedi e «te: Teel no RAS 8-0
Thickness at the elbow .. . ee ee Lee
Thickness at the middle of the rietnearaled suai 1! tops 0:6

Tail, or caudal extremity.
Extreme length, or from the last loin-wrinkle backwards,

measured on the ventral surface. . . . sis Sh gli 20 16-0
Extreme length measured on the dorsal nunbies oP iew ite BD 15:0
Distance betwixt first wrinkle and angle of terminal border. — 12:0
Breadth following curvature of terminal border . . . . — 18-0
Extreme breadth following superior curvature of skin . . 16°5 13:0
Girth, about four inches from the tip... . . . . 278 26-0
Girth, about ten inches from the tip. . . . ... 0. — 20°5
Girth at the root or hindermost loin-wrinkle . . . . . — 17:0
Notch or median terminal incision, in diameter . . . . — 0°5

Generative organs &c.
Rectum distant from end of tail . . . . . .°.). . 240 18°5
Distance from middle of anus to middle of vagina . . . 32 —
Distance from middle of anus to opening of penis . . . — 9°8
Length of generative outlet, including labia . . . . . 14 1:3
Length of generative outlet, solely the opening . . . . 09 0-9
Diameters of anus, about. . . . oie a one ORS 0°5
Breadth of each labial elevation a sdenailiad aperture . — 13
Circumference of both, ... .. 4(): ENB RO ASE ALOT 4-0
The umbilicus is distant from the anuzile sid FNRI POL, A cet 18-0
The umbilicus is distant from the end of tail . . . 2. . — 30°0
The umbilicus is distant from the middle of penal opening — 2°4

The umbilicus in the male has a cicatrix one inch long by half an inch broad.
When studying in the Stuttgart Museum I derived much information from Professor
Krauss, the able Director. Among other things he mentioned that their large stuffed

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE, 131

specimen of Manatee was the mother of our Society's young male, as attested by
Herr Kappler, of Surinam, who transmitted it. The length of the female mounted
skin I ascertained to be 122 inches, therefore twice and a half the length of the young
animal possibly six or eight months old. Another stuffed male specimen at Stuttgart
measures 94 inches. Both the above are doubtless stretched to their fullest extent ;
still one is justified in assuming the adult Manatus to be from 9 to 10 feet long.
Comparing this with Steller’s account of Rhytina, it appears that the extinct northern
form exceeded the existing American one in the proportion of two and a half to one, or
something equivalent to the difference betwixt the young and old of the latter.

3. Weight.—According to Mr. Greey the entire carcass of the Zoological Society’s
female when weighed immediately after death on board ship was 228 lb. ‘That of the
young male as ascertained by myself was 61 1b.

4, Colouwr.—This has been defined by different writers as grey, bluish grey, and steel-
grey. It is indeed difficult to specify the precise tone of colouring, which is a kind of
neutral tint, varying according to the condition of the skin. When the epidermis is
dry, the colour approaches to a dull iron-grey; but when moist, it appears more of a
dull black or sooty hue. It is best compared with that of the Elephant, to which in
other respects it offers strong resemblances, as shall afterwards be mentioned.

The anterior truncated portion of the muzzle, projecting part of the palate, and
lower lips are paler than the body, namely of a dull yellow.

IL. Tue InteEGuMENT, 1ts APPENDAGES AND SUBJACENT TEXTURES.

1. The Skin.—The coarse, hairy hide of the Manatee is one of those external features
which at once arrest attention, and claim for it kindred with Pachyderms rather than
with its aquatic congeners the smooth-skinned Cete.

The construction of the extraordinary-looking truncated muzzle having been com-
mented on by Baron von Humboldt, and freshly described by Professors Stannius and
Vrolik, I need therefore but cursorily allude to its dermal minutie. The anterior
face, and particularly its under surface, has a very warty-looking, but regular, pitted
structure. In some parts the arrangement of the furrows and ridges is of a cross-linear
kind; and in the neighbourhood of the bristly projections (afterwards to be noted) the
puckered skin assumes a stellate sculpturing. The much smaller-sized lower lip has
three or four regular transversely arched ridges and deepish intervening furrows, and in
front of these some half a dozen shallow linear grooves. The under surface of the
bulging chin is altogether smoother than the muzzle; but yet its dermis has a tessellated
superficies. The short throat has deep transverse wrinkles,

The various tegumentary folds, though passed over by authors, are worthy of special
consideration. On the upper surface of the head, and well nigh obscured neck, several
deep transverse wrinkles extend in arches from side to side.

The furrow immediately behind the muzzle is much the deepest, and especially so

132 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

towards the angle of the mouth, where it is quite a cleft. Vrolik’s figures well define
it, Stannius’s less so. Between it and the eye there is a second notable, but narrower,
groove. At the vertex another deep furrow runs round quite to the angles of the lower
jaw. Betwixt these there are shorter and shallower grooves, some of them obliquely
joining those described.

There are no very determinate upper and lower eyelids; but radiating round the
palpebral fissure are a series of crooked wrinkles. These, I have been told by those
who have seen the living animal, are twisted together in the act of closing the eye.

Vrolik’s artist has so circumscribed these ocular radii by an external dark, broad,
circular line, as to deceive any ordinary observer by the supposition that the animal has
a large patent eyeball. This deception is further heightened by a heavy backwardly
overlapping orbital fold, which certainly was not present in either of the specimens
examined by me. The text, however, corrects this misapprehension, as the author
pointedly alludes to the diminutive eye of the Manatee.

Besides those very long grooves and tegumentary areas just mentioned, a striking
feature of the head, and notably so on its upper half, are the rough scale-like patches.
These circumscribed elevated spots are irregularly shaped, though chiefly roundish,
flat on their upper surface, some smooth, others roughened or minutely pitted, as is the
rest of the skin. They vary in size from o to (.), on the vertex give a nailed appear-
ance, and on the side of the face subdivide the rugged skin into elongated and diamond-
shaped corrugations.

The pectoral extremity, as has been noted by others, is sunk into a great shoulder-fold.

As far as the elbow there are deepish transversely oblique skin-folds; but the
remainder of the limb presents only minute wrinkling. The axillary creases are
short and decussating. Both on the outer and inner aspects of the flattened limb
the surface is studded with the small warty flattened bodies spoken of as existing on
the head. In the limb, however, they are much more uniform in outline and size.
The body, from the obscurely defined neck backwards to the loin-constriction, possesses
multitudinous encircling narrow linear plaits, which run parallel to each other, and
frequently obliquely interdigitate. This gives to the skin a kind of velvety structure,
increased in semblance by the sombre tint of the derm. Behind the shoulders several
massive folds are mapped out rather than project; and these are carried from the back
round the chest. Upon the sides and shoulders tuberculated scale-patches, resembling
those on the head, are here and there distributed. Numerous short, but irregular,
longitudinal wrinkles are met with upon the throat and abdomen.

The marked broad but sudden constriction immediately behind the ribs, forming a
loin-girdle, consists below of two large hoop-like folds, the one before the other, the
anus being set midway between them, and the vulva just anteriorly in the female. As
these folds reach the back, their boundary furrows augment and increase the number of
the folds, while their height is diminished accordingly.

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 133

That portion of the subcaudal surface which, as it were, defines the fleshy limits of
the tail possesses numerous short sinuous transverse wrinkles; but the remainder of the
expanded organ is devoid of these. The upper surface is comparatively smooth. ‘The
scaly epidermal patching met with on the fore part of the body is very sparsely distri-
buted on the tail—and where present is chiefly at the margins, as small punctate
dermal tracery. All round the very posterior edge of the caudal expansion, but on the
dorsal surface, there is a smooth cord-like rim one eighth of an inch broad.

The thickness of the skin varies with its situation. Near the generative outlet I
found it to be 0°4 inch, the epidermis itself =}; of an inch’.

2. Hair and Bristles.—The sparsely distributed hairs upon the head, trunk, tail, and
extremities of Manatus and Halicore have been mentioned by all observers; I shall
but append a supplement to their remarks. Two kinds of dermal appendages have
been noted—longish pliant hairs, and short stiff bristles. The former, scattered over
the back and belly, have an average length of 14 inch; but many are shorter, though
a fair proportion reach and even exceed 2 inches. Each hair is very fine, soft, smooth,
and pale-coloured. Upon the limbs the hairs are considerably shorter than above
stated, but are closer set together, especially on the palmar aspect. On the upper
surface of the head they are likewise curtailed in length compared with those on the
body and tail. At each angle of the mouth, partially within the lips, developed on the
upper, but still more so on the lower jaw, is a pretty thick bunch of long, somewhat
coarse, hairs. Of these Stannius says that they cause the cheeks to appear thickly
beset with hair; but this neither his nor Vrolik’s sketches clearly exemplify.

These hairs within the mouth are not without interest, as, it may be, they, and not the
horny palate, are the homologues of the whalebone or baleen plates of some Cetacea.

Quite under the chin, as Vrolik shows, the hairs are stiffer than those described,
uniform in calibre, and about a quarter of an inch in length. These, both in outward
aspect and texture, are intermediate between the hairs of the body generally and the
true bristles. The latter are stout, blunt-pointed, and spring from the pits of the rough
muzzle and ridged lower lip. They vary in total length from 0:3 to 0:4 inch, though not
more than half that is free. ‘Towards the nares, where smallest, they project only
slightly, but lower down increase in size and rigidity, so that when the hand is passed
over the surface it feels like a rasp. At the dependent angle on each side of the muzzle
is a circumscribed oval prominence, half an inch in diameter, where the ridges, furrows,
and bristles are specially pronounced. This spot would seem to possess most tactile
delicacy ; for twigs of the infraorbital and facial nerves are abundant thereto. On the
semilunar, pale-coloured, tough, lower lip, there are three transverse rows of bristles
and trapezoidal ridges. Besides bristles there were many of the long silky hairs scat-
tered on the face of the muzzle, they being in greatest plenty, however, circumferentially,

’ For its microscopical composition, consult Professor Paulsen’s observations, and woodcut in Brandt’s Symb.
Siren. iii. p. 252, and Leydig’s Lehrb. d. Histol. p. 87.

134 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

The above disposition strongly reminds one of the moustachial apparatus of the Walrus;
but their shortness and rigidity render them unequal to perform the office of a sieve, as
is the case in the Pinniped: they therefore incline to the hirsute covering of the muzzle -
of the Hippopotamus.

3. Fatty Envelope &c.—The two animals differed considerably as regards their bodily
condition. The female was fat as a pig, whilst the younger male, though on the whole
plump, possessed rather an abundance of areolar and fibrous textures than fatty tissue.
In the former, immediately beneath the skin, and enveloping the whole of the body
and root of the tail, there existed a layer of remarkably dense fat. This adipose
material, under the knife, cut not unlike bacon or solid mutton suet, being rather more
greasy, however, than the latter. The pectoral limbs and the anterior portion of the
muzzle differed from the body in being almost destitute of fatty clothing, its place
being supplied by fibroid tissues. On the back the fat had a thickness of 1} inch, and at
one spot, behind the shoulder-blade, where the panniculus muscle becomes aponeurotic,
it had a depth of 2 inches. On the abdomen generally it did not exceed 1 inch thick,
thinning to $ an inch or so towards the vulva and anus. Still further backwards it
lessened by degrees, until lost in the interlacing tendinous aponeurosis forming the flat
caudal expansion. In front, over the head and lower jaws, the fat likewise diminished
gradually, so as to leave the great nasal and mandibular muscles almost superficially free
from it. As referred to in my description of the muscles, and mentioned by Stannius in
his dissection, there was a layer of softer fat intervening between the panniculus
carnosus and the muscles lying beneath. In some places, chiefly the anterior half of
the body, this exceeded half an inch in depth; but posteriorly it was considerably less
in quantity. A lump of fat covers the deep layer of fascial muscles beneath the infra-
orbital proc ss

Structurally, as Vrolik justly observes, the cutaneous fat is unlike that of Cetacea in
possessing little or no free liquid oil; and in consequence it more resembles that of
ordinary mammals. I noticed particularly in the abdominal layer a vast number of
minute red puncta. ‘These appeared to be the cut extremities of vascular twigs, the
continuation, it might be, of the subjacent rete mirabile.

I had the curiosity to weigh the fat taken from the outside of the body of the female,
and found there were 24 lb. 10 oz. This approximates closely to one ninth of the
total weight of the animal.

Desirous of judging of the flavour of the flesh of the Manatee, I had several portions
of the specimen forwarded by Mr. Latimer cooked. One or two gentlemen partook of
it along with myself; and the unanimous opinion expressed was, that it ate excellently.
When broiled, the fibre appeared white and delicate, and the flavour was that of a
crisp, tender veal cutlet. This is en rapport with the accounts of the natives, travellers,
&c., who eat it freely; and, indeed, it is said the Catholic clergy in South America do
not object to its being used on fast days, on the supposition of its being allied to the

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 135

fish tribe. Steller’s advice that the Rhytina was good food too was eagerly adopted by
the northern mariners, to the annihilation of that remarkable Sirenian race. The same
fate awaits the Dugong, since not only is its flesh appreciated in Australia, but the oil,
obtained by boiling the fat on the body, according to Dr. Hobbs of Queensland, rivals,
if not surpasses, in therapeutical excellence the better-known cod-liver oil.

II. THe SKELETON AND ITs LIGAMENTOUS CONNEXIONS.

My annotation concerning the skeleton of the Manatee shall be circumscribed, foras-
much as its osteology has heretofore been subjected to careful research at the hands of
shrewd, scrupulous, and laborious investigators. The literature on the osteology of
the Sirenia, though the order contains but four genera, Halitherium, Rhytina, Halicore,
and Manatus, with few species, stands forth prominently on account of the galaxy of
talent that has swept the field. Steller’s! early observations still hold a worthy place.
On the Lamatins, living and fossil, the genius of Cuvier, in his ‘Ossemens Fossiles’
(vol. v.), and De Blainville, in his ‘Ostéographie,’ are monuments of masterly gene-
ralization. Stannius and Vrolik and Krauss’, in their special monographs on the
American species, largely treat of the skeleton; whilst the names of Schlegel*, Owen‘,
Gervais’ and Serres, Kaup*, Brandt’, Gray*, Nordmann’, Huxley", and others not a
few, individually attest to the assiduous toil bestowed on the above group of Mammals
and the excellency of the workers thereon.

1. The Spinal Axis.

Notwithstanding what I have said, it is somewhat remarkable that no two authors
virtually agree as to the total number of vertebre in Manatus. This, it would seem,
may arise from several reasons.

1st. Computation in some instances possibly has been taken from set-up skeletons,
incomplete in the terminal caudal elements; 2nd, the number may differ in the very
young and adult animals; 3rd, the amount present may bear a relation to the sex;

1 De Bestiis Marinis. 1749-51.

2 « Beitrige zur Osteologie des surinamischen Manatus,’’ in Mull. Archiv f. Anat. & Phys. 1858; also
Archiv, 1862, p. 415, tab. xiii.; on Halitherium, by the same author, N. Jarhb. f. Mineral. 1858 and 1862.

* Abhandl. &c. Leyden, 1841. 4 Dugong, P. Z. 8. 1838, p. 28.

5 « Sirénides, Mam. Foss. du Midi d. 1. France,” Ann. d. Sci. Nat. 1841, 1846, 1847, 1849, 1850, &e., and
Zool. et Paléon. Gén. 1867-69, &e.

& Halitherium, ‘ Beitriige,’ Darmstadt, 1855-62; N. Jahrb. f. Mineral. 1838, 1856, 1858, &c., with many
illustrations.

7 «Symbol Sirenologice,”’ Mém. de l’Acad. Imp. d. Sci. de St. Pétersb. 1849, 1861, 1868, 1869, and other
papers in the Bull. d. ’Acad.: altogether a series of magnificent monographs.

8 p.Z.S.; Ann. & Mag. N. H., various; and B. M. Catalogues.

9 Beitriige, Ihytina, Helsingfors, 1861, and Act. Soc. Sci. Fennicx, tom. vi.

1 Hunterian Lectures, reported in ‘ Lancet,’ Feb. 1868. Furthermore, see extended references to literature,
Brandt, J. c. fase. iii. pp. 237, 300.

VOL. VIII.—PaRT 1. September, 1872. Y

136 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

4th, numerical variability may occur in individuals of the same species apart from sex ;
5th, if there are several distinct species, as some hold, the aggregate in each may be
different.

In reply to the first of these reasons, it is doubtless true that the tiny ossicles termi-
nating the caudal region, and each of which represents a vertebral element, occasionally
are lost; the total numbers therefore in such cases would be under the maximum.
But this only accounts for one kind of deficiency, whereas differences in numbers are
attributed to the cervical and dorsal vertebrae, where the same excuse does not hold
good. Concerning the second reason, here also non-ossification of the terminal caudals
would give rise to the very young animal having a minimum of vertebre in the spine.
But in this, as in the last, uniformity of regional numbers seemingly does not obtain.
Third, the data extant showing relation of sex to spinal formula, does not prove that
male and female possess a constant ratio the one to the other. The fourth proposition,
I am of opinion, is the true explanation of the manifold discrepancies, excepting what
concerns the cervicals. Professor Krauss, I] may affirm, has had more Manatee skeletons
pass through his hands than any other savant in Europe; and these have been received
all from one locality, and undoubtedly of one species. His observations, most accurately
made, are in every way trustworthy; and they go to show that the numbers of dorsal as
well as lumbo-caudal vertebrae are subject to irregularity. Results coming under my own
notice substantiate his data. Fifth, specific distinction yields no very determinate data
of spine-formul, especially as concerns the supposition of distinctive American forms.
It may be concluded, therefore, that the vertebral series of M/anatus is inconstant within
certain limits, and in this respect presents resemblances to those of the Cetacea.

Besides differences of opinion respecting the total number of vertebral elements,
authorities also disagree as to the numbers and character of vertebra taken regionally,
The singular J/anatus has thus afforded a moot case, every ray of light shed upon
which brings out fresh features or readings of the facts. As regards the cervical region,
two points have excited discussion :—one, whether six or seven was the normal number
of bones; the other, which vertebra was the missing one, provided the mammalian law
of seven was deviated from. The vantage-ground has latterly been ceded to those who
have maintained the presence of but six osseous representatives.

Of special observers as to the first point at issue, Sir Everard Home, Alex. v.
Humboldt, De Blainville, Leuckart', and Robert? have enunciated that there are seven
cervical elements ; whilst Daubenton, the brothers Cuvier, Meckel*®, Schlegel, Stannius,
A. Wagner’, Vrolik, Owen, Krauss, Brandt, Flower, and Gray, on more weighty grounds,
have recognized only six clearly developed neck-vertebre. In both animals dissected
by myself, only six appreciable neck-vertebree obtained. I thought I had detected the
rudiment of a seventh in the young male; but a more scrutinizing search failed to justify

* Zool. Bemerk. (Stuttgart, 1841), p. 62. ? Comptes Rendus, 1836, p. 363.
* Vergl. Anat. 4 Schreb, Siugethiere, Fortsetz. 1846, pt. 7. p. 106,

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 137

my first impression. I may further say that of very many skeletons, in various stages
of growth, examined by me in Continental and English Museums, none exhibited more
than six cervicals.

As to the second point, recognition of the absent one, De Blainville took up the
question very categorically, inasmuch as he maintained that in one of the Leyden speci-
mens he counted seven; and he assumes rather than proves that “la sixiéme, finit par
disparaitre dans son corps; l’arc restant libre dans les chairs, est enlevé avec elles.”
This statement has been contradicted by Vrolik, who cites Temminck, Schlegel, and
Peters as witnesses in evidence of its absence in the Leyden skeleton in question. In
my examination of the same specimen I certainly only found six. Professor Brandt also
throws doubts on De Blainville’s assertion ; and he himself, in a study of the Sirenian
neck-vertebre, holds, from analogy in the disposition of the cervicals of Halicore and
Rhytina, and the way in which the head of the first rib articulates, that the seventh is
that which is wanting. The first dorsal, however, or numerically the seventh from the
cranium, he is inclined to regard in the light of an anomaly—functionally a dorsal, yet
in some way a cervical. Somewhat incongruously I think, while admitting on sound
grounds but six for the neck, he would do away with this apparent exception by the less
stable assumption of a cervical simulating an undoubted true dorsal. Professor Flower,
in a short communication', very sensibly argues against Brandt’s opinion. Basing his
reasoning on the cervical irregularity extant in the Sloth, as elucidated by Bell and
Turner, and on the individual characters of the seven cervical vertebre of the Dugong
compared with those of the Manatee, he concludes that morphologically the sixth is
the missing one in the latter animal.

For my own part I venture to dissent from the above distinguished authorities ; and
suggest that it is the usual third cervical of Mammals which is the undeveloped or
absent one in Manatus. This conviction I am led to adopt for several reasons. In
Cetacea with ankylosed cervicals more generally the third is the least distinct, the
fourth, fifth, and sixth by degrees evincing greater separation. In adult Sirenia
occasionally the axis and so-called third and fourth are found partially united. In
them also the three vertebrae succeeding the axis, although subequal in thickness, do
show slight successive increment, so that, ceteris paribus, the missing true third one
would be most reduced, and its thinned body and lamina more readily coalesced to non-
detection with the enlarged axis. Again, in my dissections (vide fig. 29) I found that
there is a tiny accessory tendon of the scalenus muscle, which comes from a small
triangular fleshy slip alongside of the larger axial division, and is fixed immediately
hehind it to the same vertebra. The third nerve passes between them. This diminutive
additional tendon, therefore, completes the normal number seven of the cervical attach-
ments of the scalenus, notwithstanding there being only six well-developed neck-ver-
tebree ; moreover its relation to the third nerve is, I hold, important. Inferentially this

* Nat. Hist. Rey. 1864, p. 259.
Y¥2

138 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

and the other reasons adduced point somewhat weightily to the presumption that the
third is the deficient cervical vertebra in the Manatee.

Regarding dorsal vertebra, Krauss’s tables show 16 and 17 to be most frequent,
though Stannius records 15. I select four examples from my own observations in
support of inconstancy in dorsal vertebra and ribs. In the Stuttgart Museum there
is a skeleton of a young animal (received from Herr Kappler, 1864) of which the spinal
numbers are 6 cervical, 16 dorsal (with ribs), and 25 lumbo-caudal, =47. In the
Zoological Society's juvenile male there obtained 6 cervical, 17 dorsal (with ribs)', and
25 lumbo-caudal, =48. In an adolescent skeleton in Heidelberg Anat. Mus. I counted
6 cervical, 17 dorsal (17 ribs on left and 16 on right side), lumbo-caudal 25, but possibly
two ossicles deficient, =48 or 50% In the Zoological Society’s female the numbers (with
ribs) were, 6 cervical, 18 dorsal, and 27 lumbo-caudal, =51 in all. Excepting the Heidel-
berg specimen, the terminal tail-elements were intact, being connected by ligaments.

The so-called lumbar vertebre are two or three, according to circumstances. Thus,
one thing with the other, it results that the spinal column of the genus presents con-
flicting anomalies.

2. The Spinal Ligaments.

There is a certain amount of rigidity in the spinal column of the larger-sized
Manatus, resultant from the very limited amount of intervertebral substance. In
the older female specimen the thickness of the intervertebral cartilage barely exceeded
one tenth of an inch, the bones in consequence approximating very closely. This
deficiency of the elastic cushion of soft cartilaginous substance is not confined to
any one region of the spine, but is met with from the cervical almost to the tip of the
caudal vertebre. In the young animal there is much greater flexibility of the spine;
as, indeed, one would anticipate, seeing this is the universal rule in the Mammalia.

Counterbalancing the deficiency of intervertebral cartilage, there is an ample develop-
ment of ligamentum subflavum in all the spine-bearing vertebre. In the neck, as might
be expected from the antero-posterior compression of the six bones, it is thin, and
accommodated to the wide arches. Between the dorsal spinous processes, especially
from the fifth backwards, it is remarkably thick and strong. In some interspaces it
measured above an inch broad, and almost as much deep. From the true dorsal ver-
tebree backwards it decreases in the ratio of the size of the spines. This ligamentum
subflavum is composed chiefly of yellow elastic tissue.

The equivalent of the anterior common ligament of the vertebral column, here hori-
zontally placed, is only of moderate breadth and strength. From the seventh dorsal
segment to the lumbar vertebre the ligament in question is mainly noticeable as
existing between the keeled part of the ventral processes.

' T have to regret an error in Plate XXVL. fig. 37, where eighteen ribs are drawn. I bear due share of blame

for not detecting in time that my artist had mistaken a fibrous band coming from the cartilaginous tip of the
first lumbar as a rib; the eighteen costee in the female doubtless also misled us both at the moment.

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 139

The posterior common ligament within the spinal canal was not examined.

I observed in nine or ten of the anterior dorsal vertebre an extra ligament. This
passes as a more or less strongish band from the posterior surface or vorder of the
lower portion of the vertebral lamina to the anterior border of the transverse process,
and over the articulating process. From the fourth to the seventh vertebra it is well
marked, but is less distinct in the succeeding ones.

The capsular ligament is divided by a strong interarticular spur from the inter-
vertebral. ‘The two synovial cavities are very distinctly separate.

Of the true ligamentous bands lashing the coste to the spinal elements, each stellate
ligament is only imperfectly divided into two bundles.

The anterior costo-transverse ligaments of human anatomists are wanting.

But in all the ribs there are developed short, but immensely strong, middle costo-
transverse ligaments. These are situated deeply, and pass in an oblique direction
between the ribs and the transverse processes. They are covered by a portion of the
external intercostal muscles, and partly surrounded by the intervertebral plexus of
vessels.

Every one of the eighteen posterior costo-transverse ligaments is remarkably broad
and strong. Along with the stellate ligament the middle costo-transverse ligament
prevents the rib rotating too far forwards.

3. Limbs, Pelvis, and Ligaments.

Vrolik’s portraiture (pl. 3) and remarks (/. c. p. 69) on the progressive development
of the pectoral limb are sufficient for practical purposes. In his larger specimen the
ossific centres of the phalanges, three to each and two to the thumb, are not quite so
rigidly defined: as in that coming under my own observation. The ligaments connecting
the limb-segments are very simple, the flattened condition of the bones obviating much
differentiation ; and each joint is uncommonly lax. The tendon of the subscapularis
pierces and greatly strengthens the shoulder-joint.

The pelvic bones of two males at different ages have been delineated in the ‘ Bijdragen ’
(pl. 5); and, excepting in greater circularity of the central mass, my young male agreed.
In the older female ossification had proceeded further. The figure of the bone is
furcate or semilunar, therefore differing from the adult male, where it has an irregular
diamond-shape. The extremities of the horns are cartilaginous, the rectus abdominis
muscle being inserted between (vide fig. 50); and the posterior concave border has
likewise a cartilaginous rim, to which the ischio-coccygeus is affixed. On the inner
border the transversus perinei &c. are attached. This edge, therefore, represents the
ischium, the tuberosity being that turned rearwards; the anterior cartilages tipping
the cornua are respectively pubis and ilium. ‘The surfaces of the bone are smooth,
and indeed slightly concave; but all limb-structure is absent. The relative dimensions
of the pelvis were :—male, } inch in diameter ; female, about 14 inch in long and 1 inch

140 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

in cross diameter. Besides suspensory ligament derived from the transverse process of
what may be considered a sacral vertebra, there is another, equally strong, passing
inwards from the pubo-ischial region to the vulva, behind which it meets its fellow
of the opposite side. ‘This interpelvic bridge appears to be the homologue of a sub-
pubic ligament.

4. Cranium and Dentition.

So often has the skull of the Manatee been described and figured, that I restrict
myself to a short notice of its interior, and to a few remarks on the foetal cranium.

The sections chosen to illustrate the cranial cavity are the internal basis as opened
horizontally or with calvarium removed, and a longitudinal vertical section to the left
of the middle line. The former (fig. 36, Pl. XXV.), of the female specimen, has the
dura mater attached on the left side, but the bones have been cleaned on the right;
the latter (fig. 37, Pl. XXVI.), of the younger male, is part and parcel of the sectional
view of the body with membranes and organs in situ.

The interior basis cranii may be likened in figure to a broad stirrup, being very square
across the supraoccipital region, and arching regularly round from the temporal to the
frontal region. It is flattish below, as is the vault; but the sides of the entire cavity
are steep and but slightly arched mesially. The length and breadth of the cranial
cavity are nearly equal; but the height is rather less than either. In the female skull
(that depicted in fig. 36) the two horizontal diameters were about 54 inches, the vertical
close upon 2? inches.

The skull’s walls are very remarkable as regards inequality of thickness. The vertex,
to say the least, is as solid a piece of bone as can well be conceived, whilst the sides,
especially at the temporal region, are quite the reverse of this—namely, a thin plate of
bone. ‘To specify, and with reference to our figure, the nearly vertical section of the
frontal bone in this female was above three quarters of an inch deep, the temporal and
part of the parietal plates little more than a line, the occipital wall less than half an
inch at its middle, but thicker at the sides. The structure of the bone also varies.
The frontal is, to an extreme, dense and compact, as, indeed, is the osseous consistence
generally; only a film of diploé is apparent on the lateral walls, and the occipital
segment has a distinct (though finely cancellated) interior, with a thin outer vitreous
table.

The internal basis cranii examined, as in our figure, with the dura mater retained on
one moiety, presents a notable difference on the two sides. In that with the membrane
remaining (the left side, but right of fig. 36, as seen in the Plate) there are two subequal-
sized oval fosse, divided by a nearly transverse arched membranous ridge.

These correspond respectively to the posterior and middle fosse of, say, the human
skull. The anterior fossa of Man, in the Manatee is nearly perpendicular, or forms the
front cranial wall, and hence is only partially visible on looking directly downwards into
the cranial cavity. Those fossee present in Manatus contain the anterior and posterior

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 141

cerebral lobes. An ethmoidal elevation or ridge of bone is well marked; outside it
(partly seen in fig. 36) is the broad depression which lodges the olfactory bulb (1); the
optic foramen (2) at its posterior border is barely distinguishable. A narrow elliptical
slit (5) pierces the outer wing of the arched transverse fibrous septa, and transmits the
fifth nerve. In the posterior fossa, behind the septa and partly to the inner side of the
slit spoken of, there is a broad hollow (¢), wherein the temporal lobe of the brain lies.
About the centre of the cranial floor and within the area of the somewhat triangular
inner horn of the transverse fibrous septa from before backwards, are as follows:—a
tiny elevation representative of the lesser wing of the sphenoid; outside it a perforation
in the membrane corresponding to the sphenoidal fissure (3), transmitting the third and
fourth nerves &c.; behind that a shallow pituitary fossa (p); and lastly, posteriorly, an
oblique groove and membranous perforation for the carotid artery (ca).

About the middle of the posterior fossa, in the valley of the nodular petrous eleva-
tion, is the large internal auditory foramen(7). Rearwards of this, at the occipital, is a
wide groove running outwards and backwards, the membranous covering of which
hides the jugular portion (7) of the foramen lacerum posterius. Outwards from this, in
an angular corner of our section, are the great vascular plexus (Px) and vein which fill
the deep lateral sinus. The spinal vascular plexus (Px*), which communicates with

‘this, occupies a considerable portion of the foramen magnum.

On removal of the dura mater (as the opposite half of the figure shows), the bones of
the cranial basis display material distinction from the fossa as covered by the membrane.
They agree in most respects with the allied form Halicore, to some extent with the
young of Elephas, and certainly resemble these more than they do Cetaceans.

The frontal, fenestrated plate, and stout crista galli of the ethmoid form the anterior
perpendicular cranial wall, partly assisted below by the fair-sized orbito-sphenoid (0.8).
The cribriform ethmoidal lamella is oval, fully half an inch in vertical depth, and freely
perforated. A groove leading to the small optic foramen (2*) runs obliquely outwards ;
and immediately external to this is a large irregular ovoid perforation, separating the
orbital from the alisphenoid. ‘This interspace, one inch long by half an inch broad in
our female specimen, is partly freely open and partly blocked up by a semiglobular
projection of the dental portion of the maxillary bone (J/x), which in this case con-
tained the germs of molars.

The alisphenoid plate (As), ankylosed with the basisphenoid (Js), constitute the
mid floor; the former constitutes a part of the lateral cranial wall, being wedged
in between the squamosal parietal and tip of the orbito-sphenoid. 'The suture betwixt
the basioccipital and basisphenoid is distinct, that between the latter and orbito-sphenoid
less so. A pair of aborted nipple-like leaflets of bone appear to represent the anterior
clinoid processes; and behind these are a few foramina.

Backwards from the basisphenoid is the flat bar of the basioccipital (Bo), which,
forking outwards with the inner spur of the exoccipital (Zo), circuit the lower margin

142 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

of the great foramen magnum. But the two more interesting phases of the interior
osseous cranial construction are an immense fissure (a continuous foramen lacerum me-
dium and posterius) and as remarkable a development of the periotic (Per). The great
fissure spoken of forms a considerable segment of a circle, broad and irregularly con-
toured in front, and narrowing as it sweeps inwards and then round the periotic. It is
bounded laterally, forwards, and internally, respectively, by two divisions of the periotic
presently to be mentioned, a tip of the wedge squamo-parietal, the posterior border of
the alisphenoid, and by the basioccipital. Its narrow posterior horn, or what corresponds
to the jugular portion, dips between the posterior border of the periotic and exoccipital,
and communicates with the great inferior basal petrotympanic cavity. The massive and
dense periotic within the skull is bicuspid, and occupies nearly half the interior. The
anterior smaller division partially constitutes the lateral cranial wall, and abuts upon
the squamo-parietal wedge behind the alisphenoid. The posterior larger division (=pars
petrosa) juts across the cranial basis, as a thick nodular mass, behind the above-men-
tioned foramen lacerum medium. Its upper moiety is swollen, a prominent node marking
the semicircular canals (sc*), on the posterior surface of which is a vertical fissure
(aqueeductus vestibuli?). The lower moiety is separated from the upper by a transverse
sulcus, superior petrosal groove, near the anterior end of which is the meatus auditorius
internus (7), and above and forwards by two foramina (=hiatus Fallopius and lamina
cribrosa ?).

The great cranial fissure is ordinarily closed above by the dura mater, as has been
shown; and beneath this is a large sac, connected with the Eustachian tube, and com-
municating with the tympano-periotic fossa. The lower wall-membrane of this sac
reaches from the alisphenoid to the exoccipital and stylo-hyal cartilage, and crosswise
from the basiocciput to the tympanic.

The youngest J/anatus skeleton which I have had access to is that in the Amsterdam
Zoological Gardens, and said by Vrolik, in his memoir, to be that of a foetus.

Each half of the inferior maxillary bone apparently has had three centres of ossifica-
tion, at least is suturally divided into three areas (1, 2, 3, fig. 16)—namely, symphysial,
angular, and ascending ramal divisions. The sutural lines of demarcation spring
triradially from the proximal end of the body of the bone, and are pretty regular in
their course, that across the ramus being the longest. The frontal bone (fr) is
bilateral, as Vrolik has shown’; and a large fontanelle mesially divides the parietals
backwards to the supraoccipital. The coronal suture runs in nearly a straight line
across the vertex. A parieto-squamal suture is well defined. ‘The supraoccipital (So)
is a single transversely oval-figured bony area, quite separated from the exoccipital by
interfibrous material, and laterally bounded by broadish fontanelles (f°), which continue
backwards and divide the temporal from both. The tympanic (Zy) and squamo-malar

) Bijdragen, pl. iv. fig. 13—an upper view of skull, but which I have supplemented by two other sketches of
the same specimen (Pl. XXII.).

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATER, 143

elements of the latter are very distinct. The exoccipital (Zo) is in two subquadrate
halves widely apart, the foramen magnum (fm) being surrounded by membrane and
fibroid tissue. The basiocciput (Bo) is free, its basisphenoid articulation, as in older
animals, being unossified. Each alisphenoid (As) is disconnected from the basisphe-
noid (Bs); and behind them the membrane of the considerable-sized Eustachian sac is
left intact (fig. 17, Ews). The palatines (Pl), maxille (Mz), premaxille (Pm2), and
Jugal bones (./v) have their lines of approximate union very marked; how many ossific
centres each had I did not note. In the adult, at the outer posterior angle of the orbit,
a bony process is sent up from the jugum; this is a sesamoid or separate ossific
element (s) in the foetal skeleton.

In the above fcetus, on each side, a pair of spaces indicated the future molars in their
saccular condition, and a tiny orifice a premaxillary incisor. In our Society’s specimens
with difference of age the same conditions obtained, viz. five grinding-teeth in use and a
sixth almost erupted, whilst in the cavity behind there was evidence of at least three
more in an undeveloped state. Minute denticles representative of a pair of upper and
lower incisors I distinctly detected.

IV. THe Muscunar System.

To my knowledge Stannius is the only author who has treated of the myology of the
Manatee’; and his descriptive remarks are chiefly confined to a very general account of
the abdominal and caudal muscles. These he has compared with those of Cetaceans,
taking the Common Porpoise as his type. He briefly points to certain resemblances
between the tail-muscles of the two, shows that the cutaneous panniculus, the muscles of
the abdomen, and the so-called psoas muscles differ in the one form and in the other.
But the restricted mauner in which he traces the homologies, and the fact that he has
left unnoted the muscularly clad anterior extremity, the extraordinarily developed facial
muscles, and the large deep muscles of the otherwise shortened neck, render it
desirable that further demonstration of the fleshy structure of this singular mammal
should be placed on record.

The Manatee’s pseudo-Whale-characters (herbivorous Cete of the Cuviers and others)
and Gravigrade tendencies (of Blainville) cause me to compare its myology respectively
with Whales and the Elephant. Laurillard’s? superb delineations serve well my purpose
for the latter; Stannius’s, Carte and Macalister’s’, and my own dissections of Cetacea
abundantly supply me with material for the former.

1. Muscles of the Axial Skeleton.

(A) Those connecting the Spinal Column.—Dorsal Aspect.—I shall take the deep
fleshy and tendinous bundles upon the dorsal surface of the spine as the starting-point
whereon to build up the muscular structure incorporating the soft frame of the

1 Loc. cit. p. 34. * Recueil de Myologie, plates 272 to 295, * Phil. Trans. 1868, p. 218.
VOL. VIII.—PART I. September, 1872. Z

144 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE,

Manatee. Here we find that definition into separate or individual muscles is not easy,
from the very fused condition of the parts. There may be traced, however, through the
length of the dorsal and what constitutes the lumbar region oblique sets of fibres
which answer to those of the multifidus spine and semispinales.

The levatores costarum, corresponding to the number of ribs less one, are more easily
defined than the preceding; but they also have their fibres much intermingled with the
long spinal muscles presently to be spoken of.

As regards the énterspinales, these either are aborted or so masked by the volume of
interspinal yellow elastic ligamentum subflavum that their function is supplanted by
the latter.

From that close adherence of the mass of the erector spin to the tissues beneath,
intertransversales muscular slips are chiefly apparent in the lumbar and caudal regions,
reference to which shall be made further on.

What corresponds to the combined or continuous spinalis dorsi and levator caude
internus is a long, narrow, but, in the back, vertically deep muscle, which runs from
the neck backwards as far as the end of the tail. Anteriorly, where laterally com-
pressed but fleshy, it fills vertically the hollow between the cervical spines and trans-
verse processes. Posteriorly it becomes tendinous and aponeurotic, and is fastened to
the caudal vertebre superiorly.

There is a very massive and in great part fleshy longissimus dorsi, which extends
outside the last from the first rib backwards to the very end of the caudal vertebrae,
thus including what constitutes the levator caudw eaxternus of most other Mammals.
Like the preceding the tail-tendons are interwoven into an aponeurosis, partially fixed
to the transverse and to the spinous processes.

The well-marked sacro-lumbalis is a rather narrow but thick muscular elongation,
lying upon and firmly attached to the whole of the ribs outside their angles. Its outer
tendons are short and fixed to the coste along with the fleshy part of the external
border of the muscle; the internal tendons are even more imbedded among the mus-
cular substance. At the first rib the sacro-lumbalis is very narrow, but is broader
towards the middle of the body—in the larger specimen being 2 inches in transverse
diameter. At the last rib there is a fusiform muscle, almost like a continuation of the
sacro-lumbalis, but which I shall describe along with the subcaudal series. A few
fleshy fibres are continued forwards on to the axis, from the sacro-lumbalis, and a still
larger amount from the longissimus dorsi; but, as might be expected from the remark-
able shortness of the Manatee’s neck, neither of these compressed bundles is of much
import functionally. They are individually homologues of the cervicalis ascendens and
transversalis colli.

There is, moreover, a better representative of the trachelo-mastoid, which is a much
longer and distinct muscular band, proceeding forwards from the edge of the trans-
yersalis colli, and is inserted into the skull. ‘The cranial attachment is upon the

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE, 145

exoccipital bone, betwixt the cephalo-humeral and the complexus muscles; the united
superior obliquus and the rectus lateralis are situated below and within.

The splenius and compleaus appear almost a continuation of the long internal spinal
muscle; there is, however, a distinct separation, excepting a few of the fibres. Of
the two the splenius (Sp, fig. 8) is much the smaller. It diverges, so to speak, from
the fleshy fibres of the complexus outwardly, opposite the second rib, and proceeds
broadly to the skull, where it is inserted by a short, flat, but very strong tendon into
the exoccipital ridge above and behind the cephalo-humeral. The larger, thick and
long complexus arises from the outer side of the spinalis dorsi, above the head of the
sixth rib. It covers the remaining interspace between the ribs and the compressed
anterior portion of the spinalis dorsi forwards to the cervical vertebrae, where it spreads
out and lies superficial to the short recti and oblique muscles. It is inserted into the
whole of the back of the cranium, as far outwards as the paramastoid.

The short deep muscles of the back of the neck are well represented, in spite of the
diminution of the posterior cervical vertebre; for the atlas and axis are still of fair
dimensions. ‘They show no deviation in attachments from those of erdinary mammals.
The rectus capitis posticus major and minor have coalesced fleshy fibres, the former being
much the larger of the two. The obliqguus inferior is well developed, and somewhat
fusiform. The obliquus superior and rectus lateralis are closely united, and together
form a short fleshy band.

These posterior short muscles of the neck Stannius’ partly treats along with the
semispinales in the Porpoise; but in the Pilot Whale, Macalister’ and myself have both
found a very large rectus posticus, apparently major and minor. I have also defined
obliqui in the same animal. In the Elephant’ there are a distinct voluminous rectus
capitis major, an obliquus superior, and obliquus inferior obtain.

Ventral Aspect.—Before drawing attention to the descriptions and opinions of Rapp
and Stannius concerning the presence and homologies of the infralumbar and subcaudal
muscles of the Dolphin and Manatee, I deem it preferable to render an account of my
own dissection of the parts in question. In Manatus five, or at least four, distinct
muscular masses can be traced without difficulty, as superimposed in two broad flattish
layers, with an additional lateral or outlying fusiform one.

The first and notable muscle is that which in the profile and under-view appears as a
great and the only mass filling the interval between the last rib and the caudal extre-
mity, and the space between the chevron bones and the tips of the lumbo-caudal
transverse processes. ‘This aspect is in some respects deceptive, as the muscle, when
manipulated by the scalpel, is found to be only one of two thick and long layers
occupying the area in question. ‘The superficial stratum or musculo-tendinous lamella
arises from the outer half and inferior surface of the last rib, being here partially
overlain by the external oblique and panniculus; thence, with inwardly oblique fibres,

1 Loe, cit. p. 30. * P. Z.8. 1867, p. 48]. % Myologie, pl. 282, lettered M?, N, and N’.

Z2

146 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

it is inserted mesially from the third chevron bone, backwards to the termination of the
spinal column, and outwardly is fixed to the tips of the transverse processes. Anteriorly
the muscle is strong, thick, and very fleshy; but halfway along the tail, and nearly
throughout the middle line, it becomes tendinous, by degrees thinner, and towards the
end is little else than a dense glistening aponeurotic fascia with coarse tough fibres.
These fibres, when unravelled with care, separate into broadish tendons, one to each
vertebra, which posteriorly commingle with the great flat tail-aponeurosis.

The second or deeper muscular lamella, also taper-shaped, is as a whole much
thicker and fleshy, but not quite so broad as the last. Besides a very small slip ante-
riorly derived from the last rib, it has firm attachments along the under surfaces of the
two lumbar and all the caudal vertebre, filling the interspace betwixt the vertebral
bodies, the sides of the chevron bones, and the distal extremities of the transverse
osseous elements. This sheet, like the former superficial one, is fleshy anteriorly and
tendinous inwardly and behind. Its terminal fascize or tendons are more cord-like, and
with less difficulty resolvable into separate elements. The direction of the fibres of
no. 2 are somewhat more backwardly oblique than no. 1.

Neither of these two muscles, be it noted, passes underneath the diaphragm, but
stops short quite abreast of its posterior surface.

The next muscle (or pair of muscles) is very diminutive compared with the foregoing.
It lies on the inner and anterior aspect of the deep caudal layer, and partly passes for-
wards beneath the diaphragm. ‘The innermost and slightly longer of the two arises by
tendinous and fleshy fibres from the sides of the bodies of the last two dorsal vertebra
and of the vertebral end of the final rib; narrowing posteriorly it is inserted on the first
chevron bone. The outermost is attached in front to the last rib and behind to the
outside of the same chevron bone as its neighbour. Nerves apparently representative
of the lumbar plexus issue between these two muscles.

Lastly, if considered amongst the subcaudal muscles, and not what it to some extent
simulates, a continuation of the sacro-lumbalis, we have the lateral or superficial out-
lying fusiform muscle intermediate between the dorsal and ventral surfaces of the tail.
This numerically fifth infracaudal muscle, narrow, roundish, and tapering, has origin
close to the termination of the sacro-lumbalis, from the cartilaginous tip of the trans-
verse process of the sacral or first true caudal vertebra, and lies horizontally along the
next eight processes. It terminates in a long but strong tendon upon the surface of the
subcaudal muscle (Sc), mingling with its fascia.

My interpretation of these muscles is, that the superficial great broad layer represents
an expanded sacro-coccygeus, in this case extending more than usually forwards, and
the caudal tendons (each separate in most quadrupeds) are here coalesced into an apo-
neurotic sheet, adapted to the osseous and anomalous fleshy tail-formation. The layer
beneath is an enormously developed tnfracoccygeus, with which muscle it corresponds
in position &c. The anterior pair of small slips agree best with the guadratus lum-

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 147

borum in every respect save size. The last superficial muscle ought possibly to be
included among the dorsal series. It is evidently the homologue of a small muscle
met with by Mivart and me in Galago crassicaudatus. In that animal it lies outside the
origin of the levator caude externus, and comes from the lumbo-iliac fascia, and is
inserted by tendons on the side of the root of the tail above the sacro-coccygeus.
Doubtfully named by us’, I here denominate it in the Manatee lumbo-caudalis. I do
not recognize in Manatus any division of the infralumbar muscles agreeing with psoas
and iliacus. If these are present they are indivisibly fused with the infra and sacro-
coccygeus, and, besides, can have no limb-attachment.

The great inferior loin- and tail-muscle of Cetacea Rapp regarded as a psoas; and he
describes as costalis one of the outer dorso-caudal muscles. Meckel and others adopt
a similar interpretation; but Stannius, in his myology of Delphinus, Phocena, and the
American Manatee, opposes Rapp. He names in the former a sacro-lumbalis superior
and sacro-lumbalis inferior, a longissimus superior and inferior, a transversarius superior
and inferior, a caudalis inferior, besides intertransversarii. He regards the Sirenian
caudal muscles as nearly equivalent, more particularly laying stress on the so-called
transverse muscles, these being below, as I presume, my sacro- and infra-coccygeus, and
above the levatores.

Of the deep muscles of the ventral surface of the neck, the longus colli, which is
altogether broad and flat, may be reckoned as consisting of three triangular parts.
These, however, are not very readily separable into distinct portions; but the difference
in direction of the fibres and attachments sufficiently define them. The first or pos-
terior portion, homologous with the inferior oblique portion of higher mammals, covers
the under surface of the transverse processes of the last two (fifth and sixth) cervicals
and roots of the first two ribs. The second anterior or superior oblique slip of fleshy
fibres arises widely from the ventral surface of the atlas, and is inserted narrowly and
superficially tendinous into the rudimentary transverse process of the fifth cervical
vertebra. ‘The third inner and largest moiety of the longus colli has origin apically
from the middle of the body of the atlas, and, widening on the surface of the neck, is
attached to the inferior surfaces of the bodies of the succeeding cervical vertebre.

The rectus anticus minor is seen on the outside of the rectus anticus major, and is
fairly developed as a fleshy band whose origin is behind and beneath it cranially. It is
inserted on the outer and under surface of the atlas.

Considering the diminished extent of neck, the rectus anticus major is remarkably
large and comparatively long. As in the Galagos and other aberrant Lemurs, it extends
from the basilar process of the skull backwards to the bodies of the anterior dorsal
vertebre. In the thorax it ends in two long, flattened, strong tendons—one to the

‘ In Trans. Zool. Soc. vol. vii. pl. 2. fig. 3, lettered Jé.cd, it is regarded as perhaps an anterior prolonga-
tion of the intertransversarii caudz ; but in the tail-dissection, pl. 6. fig. 25, where fully exposed, we leave it
unlettered.

148 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

middle of the under surface of the third dorsal vertebra, and the other to the under-
side of the head of the second rib. At the cranium the muscle is fixed by fleshy fibre.
Portions of each longus colli tertius are exposed between the bellies of the recti antici
majores from the atlas backwards.

(B) Those of the Skull or Cephalic Segment: Facial or Supracranial.—The three
muscles of the face respectively recognized by anthropotomists as the pyramidalis
nast, the compressor nasi, and the dilatator naris, each and all appear to be well
developed in the genus Manatus, notwithstanding that their fibres are indefinitely
united. In the remarkably deep but narrow hollow intervening betwixt the maxillary
bone and the nasal cartilage there lies a strip of muscular fibres, much intermixed,
however, with what appears to be fatty tissue. The fibres possess a partly transverse
and partly oblique direction. At the upper part the transverse muscular structure is
necessarily short, from the configuration of the parts, but forwards from this by degrees
lengthens, becomes more oblique, and as a thick bundle fills the bony depression above
the zygomatici. Mesially situated, or upon the nasal cartilages, the fibres curve archedly
over the nares and meet those of the fellow muscle of the opposite side.

I am inclined to regard the upper narrow but deep portion of this combined muscle
as homologous with the pyramidalis nasi (see fig. 12, P.)—those fibres that cross the
naris, with the compressor nasi of human anatomy (figs. 10, 11, 12, C.n)—and the most
anterior fibres, or those that deeply encircle the aperture of the nose, with the dilatator
naris (D.n, fig. 12). These last, moreover, appear to include those diminutive human
muscles styled the levator proprius ale nasi posterior and levator proprius ale nasi
anterior.

The anomalous fibres of Albinus, or nasal rhomboideus of Santorini, may here be
represented by a longitudinal slip at the outer border of the above triadherent muscle.
The fibres of the said slip arise from the inner aspect and upper surface of the orbit,
and, running obliquely inwards and well forwards, mingle with the premaxillary portion
of the foregeing.

Unless what has been taken as Santorini’s rhomboideus is a displaced zygomaticus
minor, then there is present but one well developed zygomaticus muscle. This arises
from the deep infraorbital fossa, and is inserted into the anterior portion of the naris,
there interblending with the depressor labii superioris aleque nasi. The infraorbital
arteries and nerves, as might have been expected from the vast size of the muzzle, are
of large size, and lie alongside of and upon the zygomaticus muscle.

A levator labii superioris proprius 1 identify in a broad fan-shaped or triangular layer
of muscle, which arises apically from underneath the projecting orbit, and expands
upon the sides of the nares, front of the muzzle, and upper lip. It is much shorter
than the layer covering it, but is equally fleshy, and rather the thicker of the two; in
magnitude it is much greater than the zygomaticus, which it overlies and hides. A few
only of the fibres of the levator labii superioris proprius proceed towards and over the

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEP. 149

upper nares, the greater amount going to the lip and and anterior infranarial region.
The latter are sent inwards in distinct transverse lines, more particularly the deep layer.
The section of this part thus resembles, on a small scale, the trunk of the Elephant
when cut across—the tissue intervening between the muscular bundles and fibrille
being fatty and fibrous.

Many vessels penetrate the root and origin of this levator; this, no doubt, led Vrolik!
to regard “ the structure of the upper lip as plainly an erectile tissue.” The true action
of this muscle here may most plausibly be assumed to be a dilater of the nares.

Deeper than the last, is a broad and thick plane of muscle, which, issuing from
underneath the projecting orbit, proceeds forwards by parallel fleshy fibres, less broad
than the preceding. These wind round the anterior portion of the intermaxillary, and
lie above the buccinator, being inserted into the incisive fossa. The upper border of
this muscle, and its anterior portion, have apparently oblique fibres, which, being
difficult to dissect, are readily cut across, and have a coarse aspect. These are what
may represent the levator anguli oris, or be part and parcel of the combined levator
labii proprius and levator anguli oris—here, however, not clearly separable.

I name more than define a depressor labii superioris aleque nasi a thick mass of the
deepermost fibres of the muscle just described, and partly continuous with the zy go-
matici. These may represent, in a modified manner, the muscle in question. It is not
at all clear or distinct, excepting by an alteration in the inner and narial fibres of these
muscles. It seems to constitute a muscular layer directly in front of the intermaxillaries,
stretching from the gum round the external aperture of the naris.

The muscular layer the most superficial of those upon the muzzle, I take to be the
equivalent of the levator labii superioris aleque nasi. It is of considerable thickness and
great breadth, and almost throughout fleshy. Trapezoidal in figure, the four unequal
sides respectively form the medio-nasal, the orbital, the labial, and the muzzle boun-
daries. Fibres arise in a longish peaked manner from the outer side of the nasal
cartilage upon the superior maxillary bone ; thence they spread downwards and forwards,
part winding outwards round the orbit, and part inwards to the nares; but the main
body of the muscle has a median plane and covers the entire frontal superficies of the
nares and upper lip. Below the nasal orifices, towards the median line, the fibres pass
inwards curvilinearly, and are dovetailed with those of the levator labii superioris pro-
prius, and partially inserted into the intermaxillary bones. They likewise cross above
the nares and decussate with those of the opposite side of the face.

Concerning this muscle’s action, the attachments and direction of its fibres show that
it is an elevator, retractor, and dilater of the nares.

Mandibular Arch and Side of Skull=Infracranial—The muscles clothing the
symphysial portion of the mandible greatly increase the remarkable appearance and
unusual form of the bone of this region. Of these the levator labii inferioris is

* Memoir cited, p. 59,

150 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATER.

represented by a short but fairly developed mass of muscle and fibroid tissue, which
covers the anterior inferior blunt point of the mandible and mingles with the submucous
tissue of the lower lip.

Laterally, covering the outside of the swollen symphysis, and reaching the concavity
of the horizontal ramus, is the depressor labii inferioris, a broad, fleshy, and most
unusually developed plane of muscle. From its inferior attachment the fibres incline
upwards and forwards, and intermix with the submucous tissues of the mouth and
under lip. The two muscles of opposite sides traverse round the downwardly pro-
jecting symphysis and unite behind; but in front of this union there intervenes a
strongish connecting fascia.

The homologue of the depressor anguli oris is a thick cap of muscle which projects
on the lateral and anterior surface of the symphysial knee and overspreads the depressor
labii inferioris. The fibres of the former have quite a different inclination from those
of the latter, which cross them at a right angle upwards and backwards. The two
depressors of the angle of the mouth are connected by a wide, strong aponeurotic
fascia on the under aspect of the bone; and each as it ascends narrows, and is inserted
by membrane on the side of the lower lip.

The nerves and vessels emitted from the mental foramina are distributed to this and
the preceding muscle. They are very numerous and of considerable size.

In Whales neither of these three lower-lip muscles can be differentiated; the mylo-
hyoid and fibres of panniculus cover the rami. The moyeable lower lip of the Elephant
partially derives its power from an extension forwards of the platysmal (facien and
cervico-facien of Cuvier’) panniculus; but there is besides a broad and fleshy combined
elevator and depressor of the inferior lip’.

There is not much difficulty in recognizing the homologue of the orbicularis oris,
which, as usual, surrounds the oral fissure. Its fibres are in intimate union with the
anterior part of the buccinator and that portion of the fleshy panniculus or platysma
which covers the cheeks.

It is merely represented by a few indefinite fibres in Cetacea; but is a broad band in
the Elephant (/. ¢. pl. 274. 1), chiefly arching to the upper lip.

The buccinator (Bu) is large, long, and very thick. Its line of attachment above is
the beak-like process of the maxillary and intermaxillary bones; and below the eye it
fills the great vacuity overarched by the projecting orbit. It comports itself to the deep
bay formed by the ascending ramus of the mandible, and thence proceeds forwards, by
a broad attachment, to near the front of the upper lip. Single, thick, and fleshy in
Globiocephalus, wider flat fibres in Elephas as in Manatus.

Upon the surface of the buccinator, but inferiorly, there lies a long, ribband-like, but
comparatively thick and completely fleshy slip of muscle, which has origin from the
fossa on the anterior and inner portion of the ascending ramus. ‘The muscle in question

id

* Myologie, plate 272, 2. * Op. eit. pl. 274, n.

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 151

is covered in great part by the facial portion of the panniculus; but its fibres are quite
separate, and differ in direction from those of the panniculus. It passes downwards
and forwards between the depressor anguli oris and the depressor labii inferioris, termi-
nating among the fibres of the former and upon the surface of the latter. It appears to
counteract and check the action of the two previously mentioned muscles. Provisionally
I name it mandibularis (Md, fig. 11).

It may be remarked of the temporalis that, considering the great size of the bones
and capacity of the temporal fossa, it is relatively small, and covered with a great mass
of fat. The temporal muscle, of fair size in the Elephant’, is upwardly elongate, as is
the skull; but in Whales it is the reverse of this, being set obliquely backwards in
direction, short and thick.

There is a double masseter. The broadest and strongest portion, relatively weak in
itself, is that which, fan-shaped, and with an obliquely forward and upward direction,
stretches from the outer surface of the broad mandibular angle to the descending process
of the malar arch, where it is most strongly tendinous. The narrower deeper portion
or layer is attached to the ascending ramus and to the hinder half and lower border of
the malar arch. The fibres of this portion run counter to the upper layer; that is, they
assume a downward and forward course. Thus the linear arrangement of the upper and
lower muscular fibres is contrariwise or x -shaped, the diagonal of the forces between
which necessarily acts in an up-and-down direction.

The facial artery, nerve, and Stenon’s duct, as usual, cross the masseter, but parallel
to each other, and in a nearly horizontal line. These and the muscle are entirely
covered by the thick extension forwards of the panniculus carnosus.

In Elephas the masseter unequivocally has two layers?; the fibres, however, are more
nearly alike, and vertical, than in the Manatee. In my own dissection of Globiceps and
Lagenorhynchus 1 have considered this muscle to be single, as does Stannius* in
Phocena, with some additional fibres which he terms malaris externus; but in the
Pike Whale* the masseter is stated to consist of two planes of fibres, superficial and
deep.

(C) Those of the Costal Arches: Thoracic—The intercostal muscles, seventeen in
number on each side, are remarkably strong and fleshy. The external series are by
far the thickest of the two. They are oblique in direction, but not so much as the
internal series. The diminished length of the costal cartilages causes the above muscles
to stop short wide of the median line of the abdomen ; but, with this exceptional circum-
stance, they agree with their ordinary situation and attachments.

There is an arterial intercostal plexus, as Stannius has noted, betwixt the various ribs.
This at first lies within the external intercostal muscle, covered by the pleura costalis,
then dips between the internal and external intercostales.

Recueil, pls. 276, 287, db. * Recueil, pl. 276, j, 7’.
3 L.c. pp. 4 & 5. * Phil. Trans. 1868, p. 323.

VOL. VIII.—PART Il. September, 1872. 2A

152 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

From the extraordinary thickness of these respiratory muscles it would follow that
they possessed equal increment of power on the movements of the chest and belly.
This quality undoubtedly belongs to them; but their contractive efforts must in a great
measure depend on the coordinate action of the remarkably placed diaphragm and the
potent thoracico-abdominal muscles. The ribs are each and all firmly fixed at their
vertebral ends, although comparatively free abdominally.

The scalene muscle bounds and is closely adherent to the inner and median side of
the serratus magnus. It is a long, strong, fleshy slip, more than an inch broad, and has
origin at and partially covers the three anterior ribs from their angles inwards. In the
neck it passes along the tips of the transverse processes of the cervical vertebrae, and
is inserted into all but that of the atlas.

Although described as single, there appears to be an imperfect division into an
anticus and posticus. The attachments of the inner and smaller portion are the trans-
verse processes of the three posterior cervical vertebre and the first rib. The outer,
broader and stronger portion has three cervical tendons—namely, two large and an
intervening very diminutive one. The anterior large and small tendons, separated by
the third cervical nerve, are attached to the outstanding process of the axis; the
posterior large tendon is fixed to the succeeding vertebra. ‘The latter portion of the
scalenus in question arises from the second and third ribs and interspaces.

The rudimentary tiny slip of tendon referred to above, as being inserted into the axis
alongside but rather behind the first tendon, is not without interest. Its presence
demonstrates that the regular number of tendons exists in spite of the remarkable
deficiency of a cervical vertebra, compared with what obtains in other mammals. The
inferences derived therefrom have been discussed n connexion with the bones of the
neck.

A vascular plexus of considerable extent intervenes between the scalene tendons and
the cervical plexus of nerves at their issue from the vertebral foramina.

Rapp! says that the scalenus is wanting in the Manatee—a statement quite at variance
with my dissection. He admits its presence in the Porpoise; so does Stannius’, who
names both a scalenus anticus and posticus to the first and second ribs. ‘This agrees
with what Macalister* and I have found in the Pilot Whale; but Carte* and he only
mention a single scalene in Balenoptera rostrata. The relations of the nerves and
cervical vascular plexus in the Cete bear much resemblance to those of Sirenia.

There appears to be a double scalenus in the Elephant®—the superficial one, answer-
ing to the serratus anticus, being fleshy, of great size, and spreading upon the chest by
digitations as low as the fifth rib.

So far as strength and action are concerned, the superficial throat-portion of the
panniculus replaces the sterno-mastoid in the Manatee; but the latter muscle, notwith-

* ¢Cetacea,’ already quoted, p. 86. 2 Loc. cit. p. 86; and Meckel, vol. vi. p. 156.
* Pp. Z.8. 1867, p. 481. 4 Phil. Trans. 1868, p. 219. 5 Myologie, pls. 276 and 287. 6, 6°.

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 153

standing, is present, though greatly reduced in size. It arises as usual from the
manubrium, but in front of the pectoralis major. Hence with a diminutive thin flat
muscular belly, 3 inches long and 3 an inch broad, it proceeds forwards anteriorly to
about a level with the outer border of the scapula, where it bifurcates (see fig. 9, St.m).
The outer limb, a thin, strong, round tendon (shown in figs. 29, 50, St¢.m), pierces. the
substance of the parotid gland, and is inserted into the paramastoid; the inner fork, a
broadish aponeurosis, joins the deep cervical fascia of the neck, superficial to the carotid
artery, and posterior to the thick fleshy digastric muscle. The shortening of the neck,
great vascular rete, &c. give peculiar relations to the parts in the Manatee.

From the unusually flat and wide arched form of the ribs, the serratus magnus muscle
appears to have a different position from what it has in deep-chested animals, though
in reality it departs little, if at all, from its normal situation; it is nevertheless com-
paratively short and thin. The costal attachments are from the sixth rib forwards.
On the scapula it is fixed underneath the rhomboideus the whole length of the
vertebral border and to a triangular corner of the posterior inferior angle for about an
inch in extent. Anteriorly in firm connexion with the fleshy scalene muscle it extends
forwards, and is inserted into the outer and posterior surface of the enlarged transverse
process of the atlas (S.mg, fig. 29). The nuchal portion of the muscle has a twist upon
itself, and is overlain by the broad belly and insertions of the scalenus, so that only a
small segment of it is seen on the ventral surface of the neck when the parts are
examined in position.

The serratus in the Elephant’ is very massive, and extends backwards to the tenth
or eleventh rib. Meckel’ says it is very small in Cetaceans, only fixed to at most four
ribs; but my own researches agree rather with Carte and Macalister*® and partly with
Stannius*, in their being an apparent twisting or duplicity of the muscle and greater
costal attachment.

The latissimus dorsi, as in the Cetacea, is entirely hidden by the superimposed layer
of the panniculus, and it itself overrides in part the costal portion of the serratus
magnus. On the surface of the chest it presents a broadish fan-shaped fleshy
expausion, relatively short, upon the ribs from the fourth to the eighth; there is a
deficiency of tendon or fascia at this costal attachment, the muscular fibres being well
defined, and reaching no higher than on a level with the post-inferior scapular angle,
below the sacro-lumbalis. It continues fleshy anteriorly to where it joins the teres
major, the two muscles (as mentioned further on) being fixed together (La.d, fig. 8) to
the middle of the shaft of the humerus.

Abdominal.—Previous observers concur in noting the strange reptilian-like lengthening
of the lungs and diaphragm, and consequent relatively altered position of the heart and
upper or anterior abdominal viscera in Manatus; the same obtains in the two other

1 Pl, 267. 9. 2 Vol. vi. p. 246. 2 Memoir, p. 224.

* Under serratus anticus major, /. c. p. 13, and Rapp. p. 89.

2A 2

154 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

genera of the group, Halicore and Rhytina, examined in the flesh. From the apparent
correlation of rib-structure in the ancient Halitherium, doubtless it also was similarly
constructed.

This characteristic formation of the thoracico-abdominal parts, alluded to by many,
has hitherto not been figured, at least its position to the viscera in situ. The
desideratum I have to some extent supplied in the several sketches Pl. X XVI. figs. 44,
37, 49, and 50, and also partially in Pl. XXIV. fig. 30.

These demonstrate, as regards the diaphragm, that it extends in a retrogradent
tolerably horizontal plane from the first to the last rib, and forms a nearly mesial
septum separating the lungs within an upper, and the rest of the viscera within a
lower compartment. Altogether it is very tendinous—though Daubenton" says “je n'y
ai point apergu de centre nerveux,’ meaning, I apprehend, that there is no ordinary
free central tendon; but instead, as fig. 44, Pl. XX VI. exhibits, the elongated middle
tendinous raphe is fastened to the vertebral bodies, and to the keels from the fourth to
the last dorsal vertebra.

The fleshy portion of the diaphragm forms a narrow band on each costal margin for
its entire length. In the larger (female) specimen the muscular breadth measured one
inch anteriorly, by degrees increasing to two or more towards the posterior end. On
the inner costal wall the fleshy attachment reaches to the roots of the very shortened
forwardly median-directed cartilages (see figs. 837 and 44 respectively). Posteriorly the
diaphragm forms two short crura and pillars. The external, broader one of these crosses
outwards from the body of the last dorsal to the under surface of the hindmost rib,
partially covers the diminutive representative of quadratus lumborum, but debars
entrance of the depressores caude, though giving egress to, or rather separated by the
abdominal aorta. The diaphragm at this point folds somewhat on itself, and, fastened
to the three last ribs, but not to their tips, constitutes a pocket, by the intrusion, so to
say, of the thick fold of the external oblique muscle. The cesophageal and caval
apertures of the diaphragm are far forwards and wide apart from the crura and pockets
in question.

The deepest layer of the outer wall-muscles of the abdomen, the transversalis, has
broader and stronger fleshy fibres than the internal oblique, though less so than those
of the external oblique. It has origin in a digitate manner by attachments from the
inner surfaces of all the ribs but the second—extending inwards, and joining the
diaphragm an inch to the vertebral side of the rib-cartilages, and rather more than
that on the five posterior ribs. The muscular substance extends inwards to near
the outer third of the rectus, or to within about three inches of the middle line (fig. 9,
Tra), that measurement being equivalent to its inner aponeurosis.

A cross section of the abdominal wall shows that the fleshy part of the transversalis
and of the rectus are coequal ; each muscle thus viewed has a flattened biconvex shape, the

' Op. cit. p. 428.

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 155

rectus, as aforesaid, slightly overlapping the transversalis. The peritoneum and a slight
layer of fat cover these muscles internally ; and it is noticeable that the fat is thickest at
the median line and rib-cartilages. Between the transversalis and the internal oblique
muscles is the rete mirabile (Ad. Rete, fig. 9), which lies parallel to the inner fleshy edge
of the former.

The superincumbent layer of the internal oblique is narrow and shallow. Like the
external oblique, presently to be described, it has a digitate appearance externally, and
arises by muscular detachments from the third to the last rib; posteriorly the origins
are in close contact with those of the external oblique but anteriorly. The fleshy part
of the muscle extends inwards to the edge of the rectus, and ends in a strong glistening
tendinous fascia; this passes chiefly over the surface of the rectus to the linea alba, or
forms the anterior sheath of that muscle, which joins and is lost in that of the external
oblique. The said aponeurosis is here and there arranged in stronger bundles; and the
whole has a forward and inward direction contrary to that of the external oblique.

The external oblique muscle of the abdomen manifestly differs in appearance from
that of ordinary mammalia in not being spread in a thin uniform sheet over the whole
abdomen, but rather may be said to be relatively narrow, thick, and composed of a
series of elongated digitations clasping the extremities of the ribs. Thus it has origin,
in the manner indicated, from the cost above the cartilages, from the third to the last
rib inclusive. Its coarse fibres in broad bundles, which mask or imitate separate digitate
parts, pass inwards and backwards, and end in or are inserted by strong slips of fascia
into the outer border of the superficial surface of the rectus. These tendinous fibrille
are moreover continued in broadish strips over the surface of the rectus, parallel to the
direction of the fleshy fibres. These latter, it may further be observed, with the oblique
direction spoken of, proceed from one rib back towards the second behind it—that
is, embrace three ribs. Posteriorly the external oblique tapers in a wedge-shape
manner; and this part is inserted upon the surface of the inferior caudal muscle,
and besides, by the intermuscular fascia, deeply between the last muscle and the long
tapering muscle coming from the median side line of the ribs. Finally, the wedge
terminates opposite the second chevron bone.

In the Sirenian under consideration the rectus abdominis comports in most respects
with the condition of this muscle in the Cetaceans, e.g. Globiceps and the Porpoise.
Throughout its entire length, however, it retains its breadth more than in the Whale
tribe. This may be partly owing to the body of the latter narrowing more posteriorly,
or partly, no doubt, to the muscle itself serving mesially as a chief support of the
visceral organs in the land-waddling Manatee, the ribs of the latter being widely apart
compared with those of the former group. The rectus has origin forwards by a very
strong tendinous fascia from the outer edge of the sternum, from its projection to the
ensiform cartilage, and by some sparse muscular fibres from the first, second, and third
ribs and their sternal cartilages. At this place the pectoralis minor is immediately

156 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATER.

superficial to it, a slight portion of the pectoralis major only covering its inner edge
behind the pectoralis minor. The muscle in question occupies the inner half of the
abdomen (in the female specimen being four inches across) between the linea alba
and the cartilage-tipped rib-extremities; and posterior to the pectoral muscles, or
from the fifth rib, it is overlain on its outer border by the tendinous fibres of the
external and internal oblique muscles. Posteriorly it is inserted into the cleft of the
pelvic bone by a thickened pyramidai point.

The rete mirabile derivative from the internal mammary artery lies underneath the
rectus abdominis, as shall be described with the vascular system.

2. Muscles of the Accessory Skeleton.

(A) Those of the Shoulder-girdle—The supra- and infraspinatus are each long,
narrow, and thick; they are of about equal size. The former is inserted broadly and
muscularly into the summit and front of the head of the humerus; the latter,
narrower, rounder, and more tendinous, is implanted on the outer tuberosity.

The subscapularis occupies the whole of the subscapular fossa excepting the space
where the serratus magnus and the rhomboideus are fixed. It is entirely fleshy, and
overlaps the lower border of the bone. A short, but strong, tendon forms its insertion
into the inner tuberosity of the humerus.

The fleshy and strong teres major has origin from the lower dorsal edge and border
of the scapula, posterior to the spine. In close union with the latissimus dorsi it is
inserted into the inner aspect of the middle of the shaft of the humerus. The
latissimus partly overlaps the teres; and besides the approximation of these fibres,
there is a distinct fleshy slip which passes from the upper border of the former and
penetrates the latter close to where the tendon of insertion commences.

No teres minor was observed.

A single plane of broad, but short, muscular fibres, and but little tendon, the
rhomboideus, arises from the inner surface and vertebral border of the scapula, and
extends for an inch or more over the inner surface of the serratus; it forms a shallow,
wide muscular arch spread over the sacro-lumbalis and below the posterior end of the
limited trapezius.

A trapezius is present in the Manatee, the muscular portion of which is in some
degree circumscribed ; for although broad and fan-shaped, the shortness of the neck
reduces it anteriorly. The fleshy part is attached the whole length of the spine and
dorsum of the scapula and the acromion process; therefrom it radiates, and peripherally
is bounded by fascia which, with less distinct aponeurotic fibres than commonly
obtains in mammals, is lost in that of the dorsal region above and behind the scapula.
It is thickest and most muscular in the neck, and is fastened to the occiput.

As in Cetacea, notwithstanding the shortness of the neck, a broad, moderately thick,
but powerful muscle, homologous with the so-called cephalo-humeral, is present in the

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 157

Manatee. This has a fleshy origin from the entire length of the prominent ridge of
the outer occipital, thence is directed nearly vertically outwards and backwards,
marked by limiting the anterior flattened surface of the shoulder. It continues
obliquely round the head of the humerus immediately in front of the deltoid, at
this part resembling the latter in shape, and is inserted on the inner and anterior
side of the neck of the humerus by a very short, but strong, tendon. The humeral
attachment is on a level with that of the deltoid, above that of the pectoralis major,
and close to the front upper edge of the biceps.

Although a clavicle is absent, a muscle corresponding to a levator clavicule (?) exists.
It is a narrow fleshy slip arising from the paramastoid directly behind the stylo-hyal
and origin of the digastric. Coursing downwards and backwards parallel with the
anterior border of the cephalo-humeral, it becomes fused with this last at the head of
the humerus. ‘There is a slight transverse fibrous line of demarcation where the levator
terminates; and this, it may be, is a representative of an osseous clavicle. At the head
the muscle is in close relation with the hinder part of the parotid gland; and a small
portion of the glandular substance and several vessels separate it from the cephalo-
humeral.

The two above muscles apparently have a combined action, and drag the pectoral
extremity forwards, upwards, and fully rotate it outwards. They doubtless oppose the
latissimus dorsi and teres major; but the shortness of their leverage must detract from
any great power.

The pectoralis minor agrees with the pectoralis major in being relatively long and
narrow. It springs from the anterior portion of the rectus abdominis over the fibrous
cords or sternal cartilages of the second and third ribs, and from the projecting sharp
angle of the sternum, not reaching, however, the median line. As the muscle trends
forwards it narrows slightly, and finally is inserted into the head of the humerus.

Several large glands lie beneath the muscle; and axillary vessels and nerves pass
beneath it, the rete mirabile being closest to its deep surface.

The pectoralis major muscle is thick and powerful, though relatively narrow. It has
origin from the whole length of the sternum, and from the median line of the abdomen
two inches beyond the ensiform cartilage, where it overlaps a small inner portion of
the anterior inner edge of the rectus. The muscular fibres take a direction obliquely
or sharply forwards and outwards, and are inserted, by a very strong short tendon,
into the upper portion of the lower third of the thoracic aspect of the shaft of the
humerus. There is only an indistinct division into sternal and manubrial portions,
which might be overlooked, except that the former rolls somewhat round, or rather
dips beneath, the anterior more fleshy moiety at the axilla.

The humeral tendon of the pectoralis major while firmly implanted into the deep pit
or continuation of the bicipital groove on the inner and lower aspect of the shaft of the
bone, also possesses continuity with the radial segment of the forearm. Adduction of

158 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

the arm towards the chest is mainly effected through the upper attachment ; but increased
leverage is gained by means of the more distant fascial fixed point. The continuation
into the forearm is bya strong aponeurosis, which stretches in a bridge-like manner from
the humeral tendon over the bend of the elbow, and is fastened to the neck of the radius
at its tuberosity.

The pronator radii teres shoots obliquely over this radial insertion ; and the diminu-
tive tendon or second portion of the biceps joins and terminates along with it. On
its outer surface the aponeurosis in question is covered by and adherent to the flesh of
the brachialis anticus. The thick cord of the rete mirabile and the brachial nerves are
lodged securely, and pass downwards beneath the aforesaid aponeurotic bridge ; for as
extension of the forearm occurs the expanse of fascia is rendered tense, and thus
prevents undue pressure or strain upon the vessels beneath.

(B) Those of the Pectoral Limb. Dorsal=Extensors.—As respects the triceps,
the long scapular head is fleshy, its origin extending for one and a half inch from
the capsular ligament, to which it is firmly attached. The middle head arises the
whole length of the back of the neck of the humerus, and has a flat broad belly.
The short head occupies the whole of the back of the shaft of the bone; above
it is narrowest, and inclines obliquely inwards. ‘The three heads, as usual, unite
below, and proceed to a short flat tendon to the olecranon process,

No anconeus was observed.

The obliquely triangular elevator and retractor of the humerus, the de/totd, is of con-
siderable size and moderate thickness. Its fibres are not very coarse or disposed in
protuberant bundles as obtains in Man. Origin, the whole leagth of the short spine
of the scapula, its lower border; and it is firmly fixed to the loose acromial cartilage.
From this last point its fibres trend downwards, those behind slanting forwards,
the front of the humerus projecting beyond its anterior edge The muscle bifurcates
slightly above the middle of the humerus, at the position of the here absent deltoid
eminence; the insertions, each tendinous, embrace the biceps, and are fixed to about
the middle of the shaft; but the posterior portion continues towards the elbow.

The supinator longus is tair-sized. Origin, humerus above outer condyle, close to
the brachialis anticus. It runs along the outside of the radial shaft, and round the
styloid process, being inserted into the trapezium. It is tendinous where passing along
the radial groove, and at insertion spreads out aponeurotically. If a supinator brevis
obtains, it is with difficulty separated from the brachialis anticus; muscular fibres
apparently continuous with the latter cover the orbicular ligament and neighbourhood
a little downwards.

Extensores carpi radiales longior and brevior appear to be represented by a single
muscle with a condylar origin, a flat belly continuing three fourths the length of the
radius. The distal tendon, also flat, lies in the middle radial groove and widens out
over the carpus, being fastened into the proximal ends of the second and third digits,

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 159

the tendons of the primi internodii pollicis and long supinator obliquely crossing it at
the wrist.

An extensor communis digitorum has an origin, as usual, from the outer condyle and
ulna; its well-developed muscular mass lies mesially in the forearm, filling the broad
hollow thereon. It becomes tendinous as it approaches the wrist, and divides into
four flat broadish slips, which proceed in an expanded manner to as many of the outer
digits. That to the third finger is rather the broadest and strongest; and the two ulnar
tendons come off together somewhat higher than the radial ones.

Differentiated from the last is an extensor minimi digiti, which, like it, is flat.
Springing chiefly from the radio-ulnar ligament of the joint, it runs at first below and
then alongside the communis digitorum. Its tendon occupies the groove on the radial
side of the ulna, and at the wrist splits into two,—the short, broad, stronger division
being inserted into the proximal end of the fifth metacarpal
proceeding to the proximal phalanx of the same digit.

An extensor carpi ulnaris springs from the back of the outer humeral condyle, at first
lying upon the pollicial extensor and then obliquely on the surface of the ulna. Its
flat tendon widens as it courses round the outer distal ulnar extremity, and becomes
incorporated with the strong carpal aponeurosis. Its fibres, moreover, mingle with
those of the carpi radialis, whilst it finally has distinct insertions into the unciforme, os
magnum, and proximal end of the fifth metacarpal.

There is barely a division between what appears to represent the extensor prim
and secundi internodii pollicis. ‘The former may be differentiated as a flat, broadish-
based, lanceolate-shaped, fleshy muscle, which has origin in an oblique position along
three fourths of the shaft of the ulna. Its tendon, also broad, flat, and strong, passes
as usual in the styloid groove, and over that of the long radial extensor to be inserted
into the proximal end of the first metacarpal. ‘The latter, secundi internodii pollicis,
has also a lanceolate (but much smaller) muscular belly, which fills the deepish
interosseous interval, and at the radial groove emits a tendon which joins deeply that
of the first-mentioned muscle. The difference in direction of the fleshy fibres dis-
tinguishes the above conjoined muscles.

Ventral Surface=Flexors.—The biceps has a large, long inner muscular belly, and a
comparatively short, diminutive, chietly tendinous outer belly. The first or main portion
of muscle arises by a short, but strong, tendon from the rudimentary coracoid process.
Proceeding over the insertions of the subscapularis and the conjoined tendon of the
teres major and latissimus dorsi, it is inserted by a flat oblique tendon into the lower
third of the inner side of the humeral shaft, on a level with the pectoralis major.
The second portion of the biceps springs from the outer or anterior border of the first
belly, and, with a short rounded thin muscular development (B?), ends in a narrow tendon.
The latter is continued to the radial tuberosity, but mingles with the infundibular or

VOL. VIII.—PART I. September, 1872. 2B

the second, longer tendon

160 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

bridging aponeurosis of the bend of the elbow already described in connexion with
the insertion of the pectoralis major. ‘The thick humeral rete mirabile partially over-
lies the biceps muscle.

The coraco-brachialis is absent, or indivisibly united with the first head of the biceps.

Compared with the other muscular structures of the humerus, the drachialis anticus
is enormously developed, and, as it is entirely fleshy, causes the lower and outer
aspect of the upper limb to have unusual breadth. ‘The deltoid embraces it above ;
and lower than that the brachialis anticus occupies the outer and anterior surface of
the humerus. It moreover covers the anterior outer aspect of the elbow-joint, being
inserted muscularly into the upper half of the radius forwardly on its radial side. It
is a powerful flexor of the forearm.

The pronator radii teres is of fair size; its origin is by a strong flat tendon from the
radial side of the inner condyle; and, with only a moderate amount of fleshy belly,
it is inserted obliquely upon the inner surface of the middle third of the shaft of the
radius. Its power of pronation is very limited.

The flexor carpi radialis is long, narrow, and fiat, both in tendons and belly.
Origin, the inner condyle to the ulnar side of the pronator teres; its distal tendon
commences at the lower end of the radius, and is inserted broadly into the proximal
extremities of the indicial and pollicial metacarpals. There is no special groove for its
reception on the scaphoid and trapezium.

The flexor sublimis, profundus, and longus pollicis muscles form a complex mass,
whose origin is single and extends from the lower part of the inner condyle down the
whole length of the inner flat surface of the shaft of the ulna. The thick fleshy belly,
without possessing any clear separation, is nevertheless divisible, chiefly by tendon, into
an upper and a lower layer. The upper layer, by a semidivided expanse of palmar fascia,
supplies the second, third, and fourth digits. The fascia or united tendinous mass lies
upon and is fixed to the broad interosseous muscles, and it is continued on to the
proximal ends of the first phalanges of the second, third, and fourth digits. The
aponeurosis is not finely interwoven and smooth on its surface, but is easily torn up
into parallel coarse threads. The lower layer of this united muscle is fleshy for a short
distance further than the upper layer, and does not become tendinous until reaching
the palm, whereas the upper layer is tendinous above the wrist. It is inserted
into the third and fourth digits, being closely adherent to the superficial tendinous
mass.

From the slightly bent or oblique position assumed by the fifth metacarpal to the
ulna, and the very flat condition of bones of the forearm, the palmaris longus and
flevor carpi ulnaris appear to lie both on the dorsal and palmar surface of the
limb. They together project, as it were, and fill the angle whose two sides re-
spectively are the bones above mentioned. Origin by a flat tendon from the surface
of the inner condyle immediately above the flexor communis. The bellies commence

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 161

above the middle of the shaft of the ulna, and end in long triangular pyramidal fleshy
masses inserted broadly into the upper half of the ulnar border of the fifth meta-
carpal. At the lower part they are much compressed. They act as powerful flexors
and abductors of the manus, and give extraordinary breadth to the wrist. The palmaris
enwraps the ulnaris, and is in continuity with the tough superficial fascia of the
forearm.

The interossei are most extraordinarily well developed, contrary to what might
be expected in such an immoveable encased manus as is possessed by the Manatee.
Not only are they large, but they are also found in a manifestly double layer; and
while true flexores breves, there are also a set of dorsal interossei or extensores
breves. After removal of the palmar aponeurosis of the combined sublimis and
profundus, they are seen arising by tendon from the wrist, and altogether form a
broad, flat, fleshy sheet, which covers the palmar surface of the second, third, fourth,
and fifth metacarpals—the small flexor brevis and abductor minimi digiti muscles
bounding the ulnar side of the plane. The fibres on the second, third, and fourth
digits seem to possess a slight tendency to subdivide or divaricate; but those on the
fifth are quite single. It is possible these superior palmar muscles may represent en-
larged lumbricales or be an anomalously developed flexor brevis manus. Beneath this
another equally thick muscular layer of better-defined and somewhat double interossei
exists; they pass to all the digits, excepting the first, and are shorter than the super-
ficial interosseous layer. Part of the fibres between the second and third, third and
fourth, and fourth and fifth digits obliquely cross the intermetacarpal spaces, and
simulate dorsal interossei. These portions approximate the bones. The dorsal inter-
ossei are four, and go to the second, third, fourth, and fifth digits respectively.

The flexor brevis and abductor minimi digiti ave each represented by thin muscular
bands which run parallel to each other, arising individually from the cuneiform. The
latter partly covers the fifth digital interosseous muscle; and the former is in close
approximation with the insertion of the flexor carpi ulnaris: they are inserted by
aponeurosis together, along the ulnar edge of the fifth metacarpal.

(C) Those of the Hip-Girdle: Pelvic and Generative.—Each pelvic bone is suspended
abdominally from the first chevron process or that from the fourth lumbar vertebra, by
a strong sheet of glistening membrane, and is held in place fore and aft chiefly by two
muscles. The anterior one is the rectus abdominis, already described, which terminates
in the anterior V-shaped concavity of the female pelvis—and in the male similarly,
excepting the difference in the bone’s shape. The posterior one continues as it were
the line backwards from the rectus to the chevron bones behind the anus. This post-
pelvic muscle is a long, broad band, throughout fleshy, whose origin, in the female
as in the male Manatee, is from the posterior border of the pelvic bone. Thence it
trends inwards and backwards, passing outside and then behind the rectum towards
the middle line, where it is inserted, or becomes incorporated, with the rearward

2B2

162 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

extension of the-panniculus carnosus. Rapp’ mentions, under the head of retractor
ischii, or ischio-caudalis, that he found this in the Manatee thin and weak, springing from
the hemal spines of the first two caudal vertebrae and inserted into the pelvic bones.
I apprehend he alludes to the above-described muscle, which, as far as action and
attachments are concerned, is rightly named by him. If, however, we seek its homology
among the four-limbed and long-tailed Vertebrata, we find it representative of the ¢schio-
or mayhap ilio-coccygeus, possibly these two combined.

Stannius regards the sphincter ani as double, inasmuch as he refers to the existence
of an internal and an external anal sphincter. This I have found so far true that thick,
fleshy, circular fibres, besides its ordinary muscular coat, surround the intestine. Above
the anus, and at the external orifice, these expand broadly as they become superficial.
Virtually, less or more continuous, these may be regarded as outer and inner sphincter
from position. The same disposition and unusually developed condition of the anal muscle
is met with in Whales. In them, as in the Manatee, the gut is firmly compressed at
its outlet and above, leaving in the contracted condition but a very narrow orifice. ‘The
feces in these two groups are consequently of small calibre, and very different from the
scybalous masses of the Elephant. ‘The lower gut in it seems altogether more capa-
cious; but it is nevertheless provided with a broad muscular sphincter, as Laurillard’s
figure shows (pl. 285, Q).

I mention in my description of the panniculus that in the female a fleshy slip, about
an inch wide, is posteriorly derived from it. This offshoot of the panniculus car-
nosus, but most probably representing a separate perineal muscle, diverges from the
more backwardly extended caudal fibres about opposite the generative fissure. Di-
rected obliquely inwards towards the median line and posteriorly, it is inserted into
the fascia beneath the skin of the perineal raphe, between the vaginal and anal
sphincters. This muscle, although apparently a continuation of or derivative from the
panniculus, I regard as the homologue of the levator ani; for, besides the dermal slip
in question, an additional short portion comes from the rectal surface near the pelvis
and joins the former.

In the female a transversus perinwi appears to be represented by a longish narrow
muscle springing from the inner border of the pelvis and going forwards to the outside
of the sphincter vagine and inside and behind the lesser slip of the erector clitoridis.
In the male the levator ani and transversus perinzi were more or less united, and with
a greater transverse direction of fibre.

Other muscles connected with the generative parts in the female as follows:—a
sphincter vagine, consisting of a thick layer of fibres surrounding the vagina and
vestibule, and which are, strongest towards the perineum ; an erector clitoridis (£.c),
divisible into two slips: the external fleshy fusiform bundle arises from the apex of
the inner pelvic horn; the smaller inner slip lies alongside the last, but has no pelvic

1 Op. cit. p. 83.

9°

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 163

attachment ; both pass round the vagina towards the clitoris, partially decussating with
the fibres of the sphincter vagine.

In the male, as Vrolik’ more particularly has noted and figured, there is a well-
defined fleshy. ischio-cavernosus and long retractores penis. Moreover I readily recog-
nized a bulbo-cavernosus. While fully developed and normal in attachment, these
three muscles correspond with the somewhat altered position of the pelvis &c. from
that of quadrupedal Mammals.

3. Muscles of the Dermis.

The superficial fleshy investment to which the name of panniculus carnosus has been
given, is enormously developed in the Manatee. Indeed, as Stannius justly observes, the
ventral portion of it represents in a certain degree a supplementary belly-muscle, sup-
plying the voluminous entrails with an additional powerful support, which is so much
needed owing to the extraordinary shortening of the rib-cartilages. In the female, as
also to some extent in the younger male, the depth of muscle varied in different regions.
The muscular fibre in the former specimen, at its posterior abdominal or genital portion,
had a thickness of 14 inch; but further forwards, towards the middle of the body, it
decreased to 0°6 inch, thinning upwards on the back to 0-2 inch or thereabouts. On
the side of the neck it equalled the midventral part in volume, thickening considerably,
however, on the side of the cheek.

Although the panniculus forms a uniform whole, I shall prefer, for several reasons,
to describe it piecemeal.

As indicated above, the extensive panniculus carnosus forms a great broad fleshy
wrapper of longitudinally directed fibres, covering the entire abdominal surface (P.c’)
from the pectoral limbs backwards to beyond the anus (P.c***). On the side of the
posterior half of the body the muscle stops short of the tips of the ribs, where part of
the external oblique is exposed; but forwards from this it rises higher, the fleshy
part reaching almost to the level of the vertebral border of the scapula. The line of
demarcation of this lateral or costal border, however, is not so abrupt, as exhibited in
fig. 8, Pl. XXI., but trends, and is lost dorsalwise in a strong aponeurotic fascia. The
muscular fibres of the outer shoulder portion pass forwards along the neck and side of
the cheek, and partly become inserted by aponeurosis on the broadest surface of the
malar bone, and, partly fleshy, are continued onwards and commingle behind the angle
of the mouth with a deeper throat-layer of the muscle presently to be described.

A few inches behind the axilla the belly portion of the panniculus splits into two
segments, the outer or upper fork of which is that already spoken of as covering the
outer surface of the shoulder. From this a slip runs towards the humerus (P.c*).

The inner sternal fork, at its divarication, possesses an external tongue-shaped corner
(P.c**), mesially to which the muscle lies over the sternum (in the female being

' Bijdragen, p. 77, pls. 5 & 6. figs. 22, 23, b, d.

164 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

23 inches broad and 13 inch thick at this point); thence it passes forwards and out-
wards (P.c?) on the neck, beneath the platysmal cross fibres, ultimately being inserted
as a broad and strong tendinous sheet into the malar bone, posteriorly and inferiorly to
the first portion of the panniculus, as already detailed.

Superficial to the shoulder and sternal segments, and as it were forming a bridge
between them in front of the pectoral extremity (P.c’), is what appears as a platysma
myoides. ‘This is represented by a coarse thin sheet of muscle interspersed with much
fatty tissue. The fibres may be said to arise from the inferior median surface of the
neck and mandible for several inches in breadth, intermingling there with those deeper
segments of the panniculus mentioned above. Crossing the neck in a transverse direc-
tion, the fibres radiate slightly, and are firmly but superficially intertwined with those
of the lower border of the outer nuchal panniculus, whilst fibrous tissue and fat connect
them with the infraspinatus. A narrow slip of the muscle extends downwards on the
anterior border of the limb as low as the middle of the biceps, whence, becoming
fibrous, it descends as a cord-like body as far as the base of the metacarpal bone of the
first digit (P.c’*, fig. 13).

At the anal or posterior end the fibres of the panniculus diverge triradially (P.c***),
a broad portion curving gently outwards; and the intermediate portion (larger) ends
wedge-shaped with inwardly inclined fibres, which, along with its fellow of the opposite
side, are inserted by strong aponeurosis between the depressores caude into the sixth
chevron bone.

In the female there was also observed another fleshy slip, about an inch broad, which
was given off from the body of the muscle opposite the generative outlet; and this
proceeded downwards and backwards, being likewise inserted into the skin on the
median perineal region.

Connected with the action of this subdermal muscle it may be remarked that, as in
Cetacea, it can have little or no power over the skin itself, not being fastened thereon,
a thick coating of fat intervening. On the other hand the attachments of the muscle
point to its subserving the bodily force of various parts. For instance, the fixed points
to the malar bones must give the advanced segment of the muscle a very long leverage
for movements of the head; at the same time the insertion on the facial bones and lips
must lend power to the labial muscles, and in some ways act as a dilatator oris, and
impart additional strength to the thick muscles of the great muzzle.

V. Tue Dicestive Tract.
1. Interior of the Mouth, and Tongue.

The very curious structure of both the exterior and interior parts of the mouth has
been a favourite topic of those who have contributed memoirs on J/anatus. Stannius’s
account is, on the whole, the most explicit, though brief. In treating of the mandu-

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 165

catory and lingual apparatus, then, I propose to append to the remarks of Rapp, Vrolik,
and Stannius reference to sketches of the palatal and mandibular arches. These I have
had illustrated, I believe for the first time, both as viewed in conjunction, in a longi-
tudinal vertical section (fig. 37, Pl. XXVI.), and as separated (Pl. XXII. figs. 18 & 19).
I shall also offer some observations on the composition of the parts, particularly as
respects the so-called horny plates, and their bearings towards those of the edentulous
Rhytina stelleri.

If the section made lengthwise through the cranium, and slightly to the left of the
median vertical line, as given in fig. 37, be examined, the relations of the parts will be
easily comprehended. Confining a survey to the mouth-cavity, the lower lip, with its
sinuous, bristle-clad, thick epidermis, points forwards. Each bristle springs from a
considerable-sized lenticular hair-sac. The fibro-muscular tissues beneath are unusually
well developed. The mandibular pad (7. ¢. inner lower lip) is composed deeply of a
thick gristly or fibrous layer, and a thinner superincumbent epidermis. In front it is
separated from the outer lip by a deepish furrow, and behind stops short at the tip of
the tongue, though, as afterwards shall be shown, it is continuous with the gums. ‘The
tongue is bound down behind the pad, and is incapable of being protruded. Forwards,
from the soft membranous uvular curtain, the fleshy palate, to just in front of the
molars, is only moderately thick, whence it by degrees increases in thickness and fills
the deep concavity of the premaxillary bones, its anterior smoother portion forming the
upper inner lip-pad. This latter is separated by a deep furrow from the true bearded
lip and truncated muzzle. The palate and the said pad are equally made up of a thick
substratum of firm fibro-elastic material overlain by much thinner derm and epiderm.
What has been termed the horny plate is alone distinguishable by warty elevations.
The lips and cheeks, from opposite the superior pad backwards to the front molar, have
a clothing of long stiffish hairs, thickest set along the outer border of the gum; these
are chiefly directed downwards and backwards.

Turning now to the view of the mandible when removed (fig. 18), the outer true lip
is notably dotted with short truncated bristles and longer hairs. The coriaceous pad
has a deep and straight longitudinal median groove its whole length. Each moiety of
this is again partially divided by a wavy but shallower furrow, which anteriorly and
posteriorly curves outwards. The outer raised segments of the pad are only moderately
roughened—but the inner ones remarkably so, being studded with short, erect, hard
papille of two sorts. The larger kind are conical, and about 0-5 inch high; the
smaller setose sort are nearly as long, and abundantly fill the interstices between the
first mentioned.

The tongue quite agrees with Rapp’s statement, having long brush-like retroverted
filiform papille towards the tip, many irregularly dispersed and different-sized fungi-
form papille, and a very numerous, closely arranged, double set of circumvallate glands
situate at the root. The series of circumvallate, as noted by him, also extends linearly

166 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

and laterally forwards to the anterior third of the organ, and they lie in close approxi-
mation with the dental portion of the gum.

In the younger male the lengths of the tongue and symphysial pad mesially were
3°2 inches and 1-4 respectively, in the female 4 inches and 2; the breadth of the
tongue of the latter was 0°8, and the widest portion of the inferior pad 1-3 inch.

On the palato-dental arch (fig. 19) the cheeks and lips, as before mentioned, are
bestrewed with hair and short stiff bristles. ‘These latter form a scattered row, reaching
from the upper external labial clump (seen on the front of the muzzle, figs. 6 & 7)
backwards slightly beyond the angle of the mouth. The thick brush of hairs in the
deep hollow just outside the palate is well shown in fig. 19, 64. The long narrow
palate is divisible into three portions. The anterior, somewhat horseshoe-shaped, is
the smoothish, convex, elastic pad regarded by some as the inner upper lip. The
middle portion is the rasping horny plate, which is slightly concave longways and
across, and does not extend to the front molar by half an inch. Its surface is very
rough and warty-looking, being almost entirely covered by thick, flattish, V-shaped,
retroverted elevations. Some of these are rounder than others on the summit, many
are acerate, and all are fringed by short sete from base to tip. The intervening palatal
spaces have a less rasping surface, but are not altogether smooth. The largest V-shaped
papille in the female measured 0-2 inch long and 0:1 inch in diameter at the base.
In front and behind their size diminishes as they merge into the smoother anterior pad
and posterior palate. The posterior third portion is equal to the preceding two in
length, and is smoother; in it there is a longitudinal mesial and linear elevation, which
runs backwards from opposite the anterior molar tooth.

Leaving the histological consideration of these buccal appendages and mouth-arma-
ture for further inquiry, I shall meantime, in the superficial relations of parts, compare
what obtains in the other Sirenian genera and some neighbouring orders of mammals.

According to Huxley’, Messrs. Quoy and Gaimard? first paid attention to the horny
jaw-plates of the Dugong. Be this as it may, from their and subsequent researches it is
now known that in /alicore bristles and hairs are found in the mouth almost identical
in position with those above described. The bent-down symphysial portion of the
mandible and palatal surface of the premaxillaries are also each covered by a coriaceous
tuberculated plate ; and the tongue is bound down behind. Both Dugong and Manatee
possess a series of molar teeth; and in both, upper and lower incisors are present. But
it is further to be observed that these latter bear a gradated development, inasmuch
as in Manatus they are quite rudimentary, only discovered in the foetus, and never
protruded, whilst in Halicore they are diminutive and functionless in the female, but
two upper ones in the male form powerful tusks.

With respect, therefore, to the formation of the lips, mouth-armature, and dentition,
the homologous parts coexist in the above two forms.

} Hunterian Lectures, Lancet, 1866, p. 180. * Voyage de l’Astrolabe, 1830, vol. i. p. 146.

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 167

Of the fossil genus Halitherium, besides other observers, the valuable researches of
Professors Kaup and Krauss prove its being furnished with a full complement of molar
teeth and tusks, as in Halicore. From the construction of the palate, intermaxillaries,
and symphysial portion of mandible, I think we are justified in believing it was also
provided with horny plates akin to those of the living Sirenia. This granted, a hairy
and possibly a full, truncate muzzle may likewise have characterized it.

On carefully studying Steller’s admirable description of the muzzle and interior of
the mouth of the now extinct northern Rhytina, I have been struck with the similitude
to that of the Manati examined by myself. Indeed, excepting in size, slight variation
of the rasping-plates, and absence of teeth, what he says perfectly accords with the
formation of parts in the latter species.

It has been reserved for the very able and learned Professor Brandt, of St. Peters-
burgh, to correct the otherwise accurate Steller upon an important point, viz. the
structure of the palatal and mandibular lamine. These Steller regarded as two
osseous plates, not true teeth, but rather as it were supplying the place of these in
mastication. But although their function may undoubtedly have been trituration of
the food, still Brandt, after a very elaborate microscopic examination, has satisfactorily
demonstrated their indurated epithelial character, quite wanting in bony or dental
substance.

Steller’s figures of them when removed convey but a hazy impression of what they
must have appeared when in the mouth. Brandt’s illustration of the palatal plate in
situ, however, enables a clearer conception and estimate of it to be made. From this,
and what he himself states, the structure in question can be no other than the homo-
logue of that found in Manatus and Halicore. It certainly does not appear to me to be
the representative of teeth, nor of the baleen plates met with in the true Cetacea (an
idea some are disposed to accept). Although Rhytina was edentulous in the adult condi-
tion, I strongly suspect that, like the other Sirenian genera, rudimentary teeth may have
existed in its earlier stages of growth. Nordmann seems favourably inclined to this
opinion. The maxillary alveolar ridges are narrow and quite behind the bruising
plate, the latter occupying the intermaxillary and not the maxillary bones.

Among Cetacea the toothed and whalebone groups necessarily present differences.
As exemplifying the former, Glodiocephalus has no hairy bristles on the snout or
within the lips—these parts superficially exhibiting a moderately smooth, tough, jet-
black membrane. The alveoli are well defined, and the gum-tissues highly ridged
betwixt the numerous teeth. The front V-shaped arch formed by the junction of the
upper gums is callous, and evidently homologous with the front pad or inner upper
lip already alluded to. The anterior third of the membrane of the hard palate is dense
and fibrous beneath, and beset with irregular rows of hardened, closely placed excres-
cences; posteriorly the roof of the mouth is smoother and of a lighter colour. The
anterior part, therefore, in external appearance and structure, is the homologue of the

VOL. VIII.—PART II. September, 1872. 2c

168 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

Sirenian manducatory plate. The lower masticatory plate, again, may have its homo-
logue in the firm membranous portion of the symphysis, which is toothless.

In the Rorqual (Physalus antiquorum) bristle-like hairs are met with on the lower,
lip, and there is a protuberant chin. ‘The mucous membrane of the roof of the mouth
is indurated, transversely arched, and about a foot wide behind, but flattened, more
callous, and only half the width in front. The baleen-plates and vasculo-fibrous root-
matrix spring from outside the palate, and, though in close relation, are not a diffe-
rentiated portion of it. The baleen, in fact, at its hindermost end, is little else than a
matted tuft of hairs; and quite in front it shortens and resolves itself into isolated
patches composed of aggregated clumps of bristles, there being mesially a distinct but
small-sized pad".

We learn, moreover, from the extensive researches of MM. Eschricht and Reinhardt’,
that in the foetal and very young Balena mysticetus short stiff hairs are distributed on
the outer anterior surface of the upper and lower lips; and besides these there are
median bald spaces, apparently corresponding to the pads of Manatus. The palate is
much narrower than in Balenoptera and Megaptera; nevertheless it is strictly defined
by the raised membranous fold or “ wreathband” (Kranzband). This circumstance,
and that of the baleen-plates and matrix forming two long strips outside, and not
merely occupying the anterior midpalatal space, militate against the baleen being the
homologue of the Sirenian horny rasping-plate. The above authorities affirm that
in the foetus the subsidiary whalebone-blades “consist each of a fasciculus of hairs
agglutinated by the gum;” and as there is no special cortical tissue, this serves as “a
sufficient proof that the hairs are the primitive formation of every baleen blade.”
Hence the conclusion arises that the homologues of the baleen, in the so-called herbi-
vorous Cetacea, are the long hairs and bristles found inside the mouth, and situated, like
the baleen, lengthwise outside on each side of the palate.

Reverting to the structure of the Ruminant mouth (for instance, that of the Sheep),
the palate is smooth behind, transversely ridged (or covered by short, double, somewhat
V-shaped arches*) in front of the molars to as far as the terminal well-known semilunar
pad. ‘This last, when seen in front, quite resembles the so-called inner lip of Manatus.
The fringed part appears as the homologue of the bruising plate of that genus; and
the posterior part corresponds in each as the smooth portion of the palate. It is true
there are no hairs developed within the buccal region in the Sheep, but, instead,

1 In this species also Professor Flower (P. Z.8. 1869, p. 606) has found a fringe of short, stout, coarse fibres
or hairs basally and outside the baleen, corresponding with which in the Manatee short hairs and bristles
obtain.

? Ray Soc. 1866. Translated from the Danish Roy. Acad. Mem. 1861 and 1862.

3 Professor Turner (Trans. Roy. Soc. Edinb. vol. xxvi. p. 222) holds that these palatal folds in Ruminants are
the equivalent of whalebone. But in the Cetacea we have palatal structures with which they seem more allied ;
hence the homologue of the whalebone must be looked for external to them.

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 169

numerous conical papille, elevations of the mucous membrane, which find their counter-
part in the trapezoidal ridges of the Manatee, between which the hairs and bristles
sprout. Furthermore, from Eschricht and Reinhardt’s statement that the soft portion
of the baleen is only an excessively developed condition of mucous membrane and epi-
thelial cells, it may be presumed that the ruminant papille and the identical structure
in the mouth of Sirenia are the homologous constituents of the Cetacean gum. Con-
tinuing the comparison of parts, the pad behind the lower incisors in the Sheep accords
with the symphysial pad in the Manatee, and the fringe of roughened skin-texture on
the edge of the lower lip of the former with the broader, thicker, semilunar patch in
the latter. Both have a hairy muzzle and beard; and the cleft tendency of the upper
lip in Ovis recalls the wider, semilunar, truncated muzzle of J/anatus.

Lastly, if the oral cavity of Pachyderms be considered, homologous parts are dis-
cernible. In Hlephas the palatal pads are much softer and smaller in proportion than
in the Lamatins, the muzzle is elongated into a prehensile trunk, the lower lip is like-
wise lengthened. But long bristly hairs are largely developed within the buccal region,
especially in the African Elephant.

From the facts which have been particularized, I think that with some show of reason
the following inferences may be drawn :—

Ist. That the upper horny masticating-plate of Manatus is homologous with the
roughened, warty, or retroverted papillary portion of the palate of Cetacea, Ruminantia,
Pachydermata, &c.

2nd. That the horny baleen plates of Cetacea find their homologue in the Sirenia
and some Pachydermata, in those developments of hairs and bristle-strips within the
mouth and cheeks, existing either in bunches or as more separate filaments.

3rd. That the folds of mucous membrane within the inner upper lip of the Sirenia
are represented by buccal papille in Ruminants and other forms, and that the greater
development of similarly constituted mucous membrane in the interior of the mouth of
some Cetaceans forms the intermediate substance of the baleen.

2. Alimentary Canal.

Beyond the constrictor muscles of the pharynx to within an inch of the stomach, the
esophagus is very narrow, not large, as it is said to be in Rhytina', being no more than
half an inch in diameter in the ordinary undistended condition. But its muscular
walls are uncommonly thick at its lower end, agreeing in this respect with the Dugong,
as mentioned by Owen’. There is an outer layer of longitudinal fleshy fibres, and
beneath that the usual decussating oblique layers. For eight inches or more in the
female specimen the average thickness of the walls was a little over 0-1 inch; the
relative depth of the cuticular and submucous lining to the fleshy fibre lining is as one
to two. Near and at the cardiac orifice, however, the muscular covering increased

? Steller, op. cit. p. 310. * P.Z.S. 1838, p. 30. .
2c2

170 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

amazingly, forming, as Owen has justly said of the same structure in Halicore, a
powerful sphincter “ to defend the cardia against the pressure of the contents of the
stomach.” ‘This latter organ, indeed, is almost gizzard-like as respects its strength, of
which more hereafter. The cesophageal tube in the older female measured 10 inches
long from the posterior border of the inferior constrictor to the gastric extremity. Its
mucous membrane has quite a Cetacean aspect, there being some half a dozen longi-
tudinal furrows, and as many flattened ridges throughout its course. There are besides
innumerable very minute rug disposed in wavy transverse strie, giving a kind of velvety
appearance to the ridged portions of the tunic when in the contracted condition. The
inner epithelial lining, as Steller also has noted in Rhytina, is pale-coloured and slightly
corneous in texture. I did not observe in WManatus any of those deep glandular pits or
crypts in the mucous lining which I have found scattered here and there in the ceso-
phagus of Physalus and Globiocephalus.

Before reaching me, each Manatee had the stomach cut open and the contents
removed. Consequently this very muscular organ had shrunk considerably, and on
cursory inspection exhibited any thing but the enormous relative proportion assigned
to this viscus in its congener the Great Northern Manatee. ‘To Steller’s surprise, four
stout men with difficulty dragged out the stomach of the latter animal examined by
him. ‘The entire length of its carcass, however, was 24 feet 8 inches; and the stomach,
full of fucus, measured 6 feet long by 5 feet across. But he further notes in the table
of dimensions, ‘ Ventriculus latus seu longus potius” 44 inches. I suppose, therefore,
that this diminished capacity applies to the empty and contracted stomach, and to that
portion which corresponds to the so-called cardiac cavity of the Dugong and Southern
Manatee. If so, the cavity in question in the Rhytina has its long diameter in propor-
tion to the length of the body as 149 is to 1000, or rather more than}. In the male
Dugong, 6 feet 105 inches long, dissected by Professor Owen in 1838, the first or
cardiac cavity was 9 inches in greatest diameter, equivalent, therefore, to one ninth
the animal’s length. Taking the same portion of the contracted viscus in the female
Manatee as about four inches, this gives but one sixteenth as its proportion scale.

Of the compound stomach and bifid cecum Daubenton’s, Home’s, and Vrolik’s
original figures are suggestive, though not quite in accordance with my inspection ; nor
have they shown the interior arrangement of the parts (vide sections, Pl. XX1I1I.), which
are as remarkable as the exterior configuration. ‘The first cavity is the most capacious,
and not unlike the human stomach in shape. Immediately to the left of the esophageal
entrance, and bulging upwards to the side and partly behind the gullet, there is a pro-
tuberant cul de sac lined interiorly by corrugate mucous ruge. Beneath this is the
constricted orifice of the cardiac gland. From here, the narrowest part, the first
stomach widens to its middle, beyond the bend narrowing by degrees to the distal end,
which is guarded by a sphincter-like narrow passage communicating with the fourth
digestive compartment about its upper third. The inner tunic is composed of a pale-

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 171

coloured, thickish, tough material—mouths of gastric glands being promiscuously
scattered throughout its surface. A considerable median area has few folds; and this
smoother space with increment of muscular walls gives the cavity a gizzard-like cha-
racter. The folds of the greater end are chiefly longitudinal, and at the lesser end
increase and interdigitate more. The large cardiac diverticular gland is thumb-
shaped or cylindrical, and perforated in its long axis by a compressed central channel
with side pockets and sacculi, which wend obliquely and irregularly upwards. With
the latter there are connected short secondary recesses into which the mouths of innu-
merable small flask-shaped glands open. Thus in longitudinal section this secerning
apparatus has a dendritic appearance, whilst cut transversely it exhibits radii whose
limbs are highly convoluted. The glands secrete abundantly a viscid creamy substance,
as in the khytina and Dugong; but unlike them, as Steller and Owen mention, the
passages contained no parasitic worms.

The subequal smaller-sized tubular appendages or cornua, which may be regarded as
second and third accessory gastric cavities, are situate above and on either side of the
further extremity of the lessser curve of the first stomach. Their parietes are only
moderately thick, their internal coat chiefly thrown into longitudinal folds; and the
two chambers, by thick-walled passages, end together in a pouting enlargement (com-
parable to the os uteri) at the summit of the fourth gastric compartment. ‘The latter,
elongate and intestiniform, possesses a series of softish, florid, mucous plications abun-
dantly glandular, and sinuously longitudinal and furcate. The pylorus is a firm ring.
The duodenum has a moderate expansion and a relatively smooth inner coat for several
inches; the pancreatic and common bile-ducts enter wide apart.

The empty small intestines have an average diameter of rather over half an inch; and
their muscular coat is uncommonly thick. In the female their length is 25 feet, and in
the younger male 24 feet 4 inches. WValvule conniventes are absent; but commencing
near the duodenal loop in the circumference of the gut are five or six longitudinal mucous
ridges, which, with sinuous lines, continue straight on as far as the ileum. Between
these are short transverse interdigitations and corresponding depressions. Each short
Peyer’s patch is from } to 1 inch apart; and, besides being distributed in an opposite
zigzag manner as obtains in Halicore, they follow straight lines in the long furrows.
In the ileum the longitudinal rug frequently fork and pass obliquely to each other;
and the short spurs from these enclose in profusion scattered loculi and glands of
Lieberkiihn. The ileo-cecal orifice is guarded by a powerful tumid muscular sphincter; -
and there is a pouched ileo-colic agminate gland resembling that of the Giraffe and
Hippopotamus. The cecal appendages are thick-walled, ridged, glandular within, and
outwardly look like a pair of conical teats. Lengths 1} and 1} inch and 0°65 inch
in diameter, and their roots 1 inch from the ileo-cecal valve. At the commencement
of the colon there is a dilatation for a couple of inches or so, with a diameter of above
three and a half inches distally, where it is constricted; and then follows a second, but

172 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATER.

narrower, expansion. The first is very glandular, and with convolute ruge; the second,
thinner walled, assumes interiorly the character of the rest of the great intestines.
These in the female, including cecal appendage, are 17 feet 9 inches long, and in the
male 18 feet—the greater muscular contraction of the former probably accounting for
the difference. The ruge are very numerous, close-set, and chiefly longitudinal, and
obliquely interdigitate, forming shallow elliptical depressions, among which are glan-
dular patches. Halfway on the gut the ruge and glands diminish in size and number.

To supply a desideratum as regards the abdominal viscera in their natural position, I
have given in fig. 20 a reduced copy of a diagrammatic sketch taken from the young
male animal. It represents the parts as seen when a median longitudinal section has
been made from near the anus forwards to the middle of the sternum, the fleshy walls
being dragged outwards. Anteriorly the heart appears to occupy the full breadth of
the chest, the severed pericardium stretching across at its bifid apex. Behind is the
liver, segmented into four divisions,—a very large triangular portion of the right and
another equal-sized portion of the left lobe filling respectively the right and left sides
of the cavity ; whilst between them, in the triangle bounded by the pericardium and
their anterior borders, are two much smaller lobes, the right one of which contains the
rather large gall-bladder. No lungs or diaphragm are exposed, the apparent and not
real absence of the latter doubtless having deceived Dr. G. A. Perkins! in his examina-
tion of Wyman’s” Janatus nasutus. Mesially situated and betwixt the hinder fork of
the great liver-masses, a small piece of the stomach and curved appendix are exposed.
The remaining posterior half of the abdominal cavity shows only intestinal coils, and
partially the urinary bladder when this viscus is distended.

When, however, the thoracico-abdominal cavities with the entrails in situ are
examined sidewards, a representation of which has been given in the body-section
(fig. 37, Pl. XXVI.) with the ribs in place and the intervening tissues removed, a
widely different view is obtained. ‘The relations of the parts mentioned (heart, liver,
intestines, and bladder), to some extent, remain good. But above them is brought out
in relief the enormous lung, which reaches from the first to the last rib, and extends
more than midway downwards, just permitting a fringe of the elongated diaphragm to
peep through below and be the barrier line betwixt the dorsal pulmonary and ventral
cardo-alimentary compartments.

3. Glands concerned in Digestion.

Of the secretory apparatus connected with the mouth, the most conspicuous bodies
are the parotid glands. As briefly noted by Stannius, these are very large and lie at
the sides of the lower jaw. They have a coarse granular texture, are broad and flat,
and reach from the insertions of the cephalo-humeral and levator claviculi muscles
forwards to beyond the angles of the mandible. In the vertical and horizontal direc-

* Proe. Boston Soe. Nat Hist. (1845-48) vol. ii. p. 198. * Ibid. vol. iii. p. 192.

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. bia

tions they stretch from the temporal part of the malar arch downwards to the digastric
muscles and the stylo-hyoid cartilages. A portion of each gland also wraps round the
stylo-hyal rod, and dips into the hollow continuous with the foramen lacerum posterius.
The internal maxillary artery dips beneath them and forms a vascular network, partly
enveloping their deep and superficial surfaces; while behind is the cervical rete mirabile.
The narrow tendinous cord of the sterno-mastoid pierces and goes quite through the
posterior half of each gland. Superficially the neck and cheek portions of the fleshy
panniculus cover and completely hide the parotids as well as their Stenonian ducts.

The submaxillary gland is also flattened, and of no mean size. It has a horseshoe-
shape, the anterior convexity of which is lodged in the postsymphysial angle, whilst
the posterior concavity reaches the transverse bar of the hyoidean arch, and partly
covers the thyro-hyoid muscles. But the body of the gland chiefly lies upon the mylo-
hyoidei, the two limbs of the crescent filling the deep hollows of the mandible in front
of the angles. At this latter point, however, a portion of its substance is in close apposi-
tion with the anterior twigs of the inframandibular plexus of vessels, with the facial
artery, and with the subjacent pterygoidei.

I regard as representatives of sublingual glands a series of partially separate, small,
lenticular bodies, which lie near and backwards from the frenum lingue ; but I did not
detect their excretory duct. My observations support Rapp’s account of the tonsils,
viz. flat elliptical lamin, their numerous orifices having a sieve-like aspect. ‘The
velum pendulum palati is a broad membranous fold without appreciable uvular
thickening of muscular fibres.

The pale-coloured firm pancreas has the usual situation, within the duodenal loop.
Its duct opens into the intestine close to the pylorus.

The liver of the larger specimen had been hacked in pieces, so that nothing but its
weight, 3} lbs., and apparent long diameter, fully 8 inches, could be made out satis-
factorily. In the younger male this gland was more intact. Its relative position towards
the neighbouring organs has already been mentioned. Vrolik’s description of the
Manatee’s liver corresponds more with what I have found than does Daubenton’s:
the latter having but examined a feetus may account for this. Jn situ, but still more
so when removed, the entire liver has great resemblance in shape to the inflated lungs
of an ordinary mammal. Thus the posterior broad surface of the main right and left
lobes forms a deep arched hollow, enclosing the stomach and duodenum, and which may
be compared to the dome-shaped concavity of the lungs as they rest on the diaphragm.
The anterior partially segmented lobules and the gall-bladder simulate the upper
pulmonary lobes overlapping the base of the heart. What I gather from Steller’s and
Owen’s words concerning the mainly trifid hepatic organs of Rhytina and Halicore
leads me to infer that this gland in Manatus differs little, if at all, from them. In the
latter the two large somewhat triangular and much separate right and left lobes possess
few emarginations. There is a short, shallow notch on the middle of the ventral

174 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

margin of each; and the left possesses a small subtriangular lobule at its posterior
spinal corner. The third smaller anterior and semidivided lobe, transversely bitrian-
gular or oo-shaped, Steller’s anvil-formed and Owen’s quadrate-figured portion, may
either be regarded as the homologue of the so-called cystic lobe of some mammals,
or as representing additional upper or anterior lobules of the right and left lobes,
bridged together by a diminutive lobus qguadratus. This last, as in the human subject,
is that portion bounded dorsally by the transverse fissure, laterally by the gall-bladder
on the one side, and the round ligament and short longitudinal fissure on the other.
There is a compressed boot-shaped diminutive lobule immediately to the right of the
inferior vena cava, and a second rather elongate, but terminally flattened, lobule
attached to the left wall of the same vein. Both of these small lobules spring from
the root of the main right lobe, and respectively appear to be homologous with the
caudate and Spigelian lobes.

Owen remarks that the small Spigelian lobulus in the Dugong is continued from the
root of the left lobe. This origin, however, according to my observations in those
mammals where the liver is deeply cleft, would not precisely correspond with the
Spigelian lobule, which arises from the right moiety, and is separated from the left lobe
by the ductus venosus. Notwithstanding, it does not militate against the Professor’s
clear definition that “the homologue of the ‘ Spigelian lobule’ is shown by its relation
to the lesser curvature of the stomach ”?.

All the hepatic fissures are shallow. The most marked ones, the longitudinal and
that of the ductus venosus, being filled up by strong fibrous tissue, covering the vessels
therein. As to the ligaments, the suspensorium hepatis is moderately broad, and firmly
fixes the organ to the pericardium and the diaphragm. ‘The round ligament, as usual,
forms the anterior or ventral one positionally. In the young male it was a narrow
cord, nearly impervious, 1 inch from the liver. The two lateral ligaments diverge
from the vena cava, and traverse lengthwise the right and left lobe about an inch
outside their vertebral margins.

The pyriform but forwardly projecting gall-bladder lies superficially on the ventral
aspect of the small anterior right lobule. When distended it is 2} inches long and
1 inch in diameter at the fundus. The cystic duct, of considerable calibre, winds in an
S-shaped manner, and at about three quarters of an inch distance from the neck of the
gall-bladder receives singly the united hepatic duct on its left wall, as Daubenton and
Vrolik have recorded. In the Dugong the cervix of the gall-bladder is said to be
obliquely pierced by two hepato-cystic ducts, entering, as the ureters do, into the
urinary bladder. The ductus communis choledochus in the male Manatee was as thick

as the barrel of a goose-quill, and penetrates the intestine about three inches from the
pylorus.

‘©The Anatomy of Vertebrates’ (1868), vol. iii. p. 483. See also Owen “ On the Anatomy of the Cheetah,”
Trans. Zool. Soc. vol. i. p. 131,

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE, 175

On section the liver exhibits a fine glandular structure, and not a coarse lobular
substance as in some Ruminants. ‘The interior of the gall-bladder is smooth.

VI. OrGANS OF CIRCULATION.
1. The Heart.

The following tabular arrangement expresses in inches and tenths the several dimen-
sions of the heart of the female Manatee when contracted as ordinarily after death, in
this case, however, having been very slightly preserved in spirit :—

Right auricle. Left auricle. -

PiireMaesleme i: ce 2 acai ES! tioned: (iteleld tage Le 16
PisiremexDKendthy esi ccs), et ye yeisy sy Nils ignag >. Lee 15
Right ventricle. Left ventricle.
Extremelength, anteriorly . 9. . « . »« «) a4 2°8
Extreme length, posteriorly... ... . . . 20 >. 258
Extreme breadth at base, anteriorly . . . . 27 2°3
Extreme breadth at base, posteriorly. . . . 2:4 2°)
Eixtremesbreadthvat apex: 2.4.) . sa) so) se VL 15
Extreniesthickness of walls: sn.) 4.0 sy, 4 oy 20 15

This organ has been so repeatedly described that I can add nothing material to the
statements of previous observers, and agree with them as to its cleft nature.

2. Blood-vessels and Lymphatic Glands.

The arterial distribution of the American Manatee has been so lucidly explained in
the masterly compendium on the vascular system by Professor Hermann Stannius', that,
were it illustrated, I should be content to leave the subject untouched. But the
remarkable character of the vessels, splitting up, as they do, in certain parts into multi-
farious plexuses and rete mirabile, is a sufficient reason why they should be figured and
further commented on.

According to the above author, and as my dissection (fig. 30, Pl. XXIV.) demon-
strates, a short, wide, innominate trunk springs from the arch of the aorta, and divides
into a right subclavian and common carotid. From the summit of the arch the left
common carotid is derived ; and, lastly, further beyond is the left subclavian. As regards
the carotid and branches, he states only that the common carotids have tolerably long
stems, which, at first glance, appear to simulate division into an external and internal
carotid, although this does not truly take place. The first main branch of the carotid
proceeds inwards, and supplies the larynx, the hyoid apparatus, and the tongue.

What I have found obtain is as follows:—The stem of the fair-sized common carotid
is branchless until about opposite the deep hollow in front of the shoulder or supra-
' Op. cit. p. 31 et seq., also Von Baer, Mém. d. ]’Acad, St. Pétersb, 1835, tom. ii. p. 199,

VOL. VIII.—PaRT 111. September, 1872, 2D

176 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

scapular region, where an artery (transverse humeral) of small calibre strikes directly
outwards, and terminally subdivides into a broad radiate rete mirabile, covermg the
subscapularis, supraspinatus, &c. The single arterial tube is superficial to the cervical
nerves, but is itself enwrapped by portion of the vascular neck-plexus. Beyond and on
a level with the cricoid is a division apparently equivalent to internal and external
carotids. The former dips in among the rete mirabile at the posterior base of the skull
just behind the cranial series of plexuses. Among others, one occupies the poste-
rior portion of the great fissure between the occipital and tympano-periotic bones ;
and whilst mingling with the cervical and spinal rete, complex branches are lodged
within the skull at what corresponds to a groove or recess of the lateral sinus, where
also venous channels obtain. The external carotid at the stylo-hyal and under cover of
the digastric and parotid gland bifurcates; and plexuses are derived from both of these.
The branch agreeing with the facial runs towards the angle of the mandible and at the
concavity of the body of the bone turns upwards and is distributed with a plexiform
arrangement on the face. From its proximal end, and in fact enwrapping it, are retia,
which may be regarded as submaxillary, submental, &c. subdivisions; and these lie
within the concavity of the jaw, twigs supplying the muscles and other parts, while
some inosculate with their fellows of the opposite side. The other, widest branch of
the external carotid ascends behind the mandibular angle, previously supplying plexi
to the parotid gland, superficies of the digastric, &. Other plexi, which were not
followed in detail, spread over the tympanic, temporal, and malar areas. At the ptery-
goid region there is separation of the external carotid into several thick retial bundles,
whereof the inferior dental, lingual, and internal maxillary are most conspicuous by
their volume. ‘The vascular network, as it pierces the large vacuity of the lower jaw, has
a remarkably open character, resembling a meshwork of fibrous tissue ; and, as in Cetacea,
the interstices are partially occupied by fatty tissue and nerves. This vasculo-nervous
mass issues at the mental foramen, and supplies the lower labial parts. The numerous
capillaries of the internal maxillary division pass on to the pterygo-maxillary fissure,
and send inwards superior dental arterioles ; whilst the main mass, lying in the lateral
groove of the maxilla, is continued on through the orbit and emerges at the infraorbital
foramen, spreading amongst the fleshy and other structures of the face and snout.
Ciliary branchlets from the above are given off to the eye &c.

Stannius says that the subclavian artery divides into two main branches—a de-
scending large internal mammary, and the axillary. Before these divide, a very short
twig is sent upwards over the head of the first rib. Both arteries are equally split up
into narrow channels, which intertwine among the rete mirabile of the cervical region
and thorax. Von Baer likewise shows that the axillary artery becomes broken up into
minute vessels which overlie and are partly distributed to the shoulder and partly
continued on to the anterior extremity, mingling like the last with the rete cervicale.

This is certainly the case, and the complexity and quantity of parallel channels is

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. LT

truly astonishing. Besides an axillary, however, I observed another trunk derivative of
the subclavian, and which may be representative of a thyroid axis, terminating in axillary
rete. In tracing continuations of the axillary rete I could distinguish circumflex
anterior and posterior bundles. The brachial rete diminishes as it reaches the elbow
and passing beneath the pronator radii teres, forms an ulnar rete. This keeps close to
the bone, under the forearm-muscles, and crosses obliquely to the proximal end of the
fifth digit. Here, besides muscular radicles, a bunch goes to the palmar aspect of the
wrist, and by intricate partition helps to constitute the palmar arch. The radial rete
appears less complicate, but unfortunately its manner of palmar division was not satis-
factorily made out.

The multitudinous networks, nuchal, spinal, thoracic, and caudal, are sufficiently like
those of whales, and have been so frequently referred to by other authors, that I need
not dwell on them. As regards the intercostal plexuses, these do differ from those of
Cetacea, inasmuch as, instead of great contorted coils lying superficial to the ribs, each
intercostal artery dips singly between the ribs, and in the space covered by the pleura
and muscles divides arborescently. With all due respect therefore to the accuracy
and acumen of our great leader, Professor Owen, I venture to predict the presence of
similar rete in the Dugong, where such arterial modification is denied. When unin-
jected the closely-packed vessels so simulate coarse muscular fibre as readily to deceive
one unless critically inspected.

There is an abnormal rete, hitherto unrecorded, in continuance of the internal mam-
mary. ‘The latter vessel issues beneath the rectus abdominis, opposite the third costal
interspace, and proceeds upon the transversalis as a rete, which posteriorly anastomoses
with a returning epigastric series. Anteriorly the rami run outwards in parallel radii
like the plume of a pen. The abdominal surface of the posterior half of the diaphragm
is supplied with vessels and nerves arranged in a like fashion. I may advert to a retal
offshoot of the deep lumbo-caudal mass of vessels, which, for distinction’s sake, may be
named either sacral, pelvic, or hypogastric rete. Derived from where the costal channels
strike within the chevron bones, it forms a thin but wide sheet of arterial and venous
rami, which cover the sacro-coccygeus and parts beneath the urino-genital organs.
From it vesical and other supplies are given off, the most characteristic being a hypo-
gastric, obliterated beyond the fundus of the bladder, a uterine, and in the male sper-
matic plexus, with marked arteria dorsalis penis.

Circumstances already mentioned prevented my observance of the giving off of the
abdominal aortic trunks or following the visceral distribution. ‘The mesenteric vessels
appeared to split into primary, secondary, and tertiary arches without any striking
peculiarity in the vasia brevia, and the hemorrhoidal arterioles have inosculations with
the hypogastric rete.

The veins of the face and head were not followed in detail. Branches, however, were
observed to return from the submaxillary region and outer side of the jaw; these con-

2D2

178 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATER.

verge below the parotid gland and join the external jugular opposite the paramastoid.
The brachio-cephalic vein comes inwards from above the insertion of the pectoralis
minor; and another marked tributary is derived from the vascular plexus covering the
inner subscapular region.

The course of the external jugular vein is from behind the cranial end of the stylo-
hyal and the thereupon attached portion of the digastric muscle, backwards and slightly
obliquely outwards, uniting with the internal jugular near the first rib. The external
almost equals the internal jugular vein in calibre; and it lies over the tendon of the
sterno-mastoid muscle and the suprascapular artery.

The internal jugular vein commences at the cranial aperture, foramen lacerum
posterius, near to the attachment of the rectus lateralis and cephalo-humeral muscles,
where there is a large venous plexus as in Cetacea. As it traverses the neck backwards
it lies chiefly to the inner side of the carotid artery, crossing it, however, about the
level of the bifurcation of the trachea, posterior to which it converges to the large
innominate trunk formed by it, the external jugular, and the subclavian vein. There
are several oblique bridging communications between the ecto- and entojugular veins.
No valves were observed in the above veins of the neck.

The deep cervical glands are very voluminous, and fill the intervening cleft, bounded
anteriorly by the cephalo-humeral muscle, externally by the subscapularis, deeply or
dorsally by the short neck-muscles, the lateralis and obliquus externus, and within or
mesially by the extension forwards of the serratus magnus. The cervical plexus of
nerves passes over the glands in question, the latter being enveloped amidst the rete
mirabile.

VII. Vocau anp Respiratory APPARATUS.
1. The Air-passages.

Stannius has been successful in his exposition of the structure of the larynx. I may
refer, however, to two points he and Rapp have failed to notice, viz. the existence of a
small recess or pseudo-sacculus laryngis at the anterior extremity of the vocal cord, as
in the Dugong; and to the presence of small nodular cornicula laryngis or cartilages of
Santorini, surmounting the arytenoid bodies. As these authors and’ Vrolik state, the
epiglottis, unlike the Cetacean, is of the most rudimentary character; the thyroid car-
tilages are united anteriorly by a narrow bridge, and anterior and posterior cornua are
well developed; the cricoid is a complete ring posteriorly, very broad, and with a
marked prominence for the attachment of the thyroidal posterior cornu; the arytenoids
are trihedral; the vocal cords are the reverse of prominent, and deficient in inferior
excavation. ‘The several ligaments are composed of tough yellow and fibro-elastic
tissues; and the diminutive epiglottis, curiously enough, consists of like material, void
of a cartilage basis.

The dozen tracheal rings, and, as far as I could make out, the bronchial also, are not

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 179

continuously spiral, as obtains in /Halicore, but, as Stannius figures in Manatus, there
are some which bifurcate and obliquely cross the long axis of the tube. In my female
specimen the trachea, 3 of an inch in diameter, split at about 5 inches distance from the
lungs, and each bronchus entered almost at the summit of the pulmonary organ. Within
the lung it goes in a straight line to the posterior extremity, lying a little to the inner
side of the middle. About a dozen bronchia branch outwards, these again subdividing
in the pulmonary substance.

There is a narrow and moderate-sized thyroid gland on each side of the upper portion
of the trachea.

The lungs, their shape and singular relation to the diaphragm, &c. have often been
commented on since Daubenton’s original description. My illustrations of the parts in
their natural position, figs. 20 and 57, supplant verbal detail. Some two or three inden-
tations, $ to 1 inch deep, are the only trace of segmentation; but anteriorly they ter-
minate in a short rounded lobule (J, fig. 41). In the uninflated state the greatest thick-
ness of the lung-substance of the female was 1 inch; extreme length 25 inches;
breadth towards the anterior extremity 2? inches, about the middle 34 inches, and
rearwards 13 inch, tapering finally to an obtuse termination sunk in a pocket at the
lumbo-vertebral end of the diaphragm.

2. Hyoid and the surrounding pharyngo-glossal fleshy parts.

The hyvidean arch comprises three bony pieces—to wit, a small, flat, oval basihyal,
and a pair of long subcompressed stylohyals. Each of the latter measured 1:7 in the
young male, and 2:2 inches in the older female. ‘To the upper narrow extremity of
the stylohyal a strip of cartilage an inch long is fixed, by which it is fastened to the
inferior tubercle of the exoccipital. Betwixt the other (broader) end of the bone and
the basihyal is a >-piece of cartilage representative of ceratohyal. This extends con-
tinuously along the outer border of the basihyal, and forms a retrocurrent wing to it on
either side; and to these the anterior cornua of the thyroid ale are attached. The
thyrohyals or connecting ligaments between the hyoid and larynx are tough thickish
membranes, and apparently contain a considerable amount of yellow elastic tissue.

I examined the intrinsic muscles of the larynx carefully, and found that, notwith-
standing the rudimentary nature of the epiglottis and comparative absence of laryngeal
pouch, I could differentiate superior and inferior aryteno-epiglottidei, and even noted
fibres equivalent to a thyro-epiglottideus. Indeed, each and all of the laryngeal muscles
are relatively well developed. The extrinsic laryngeal muscles maintain a fair size,
with attachments of the ordinary kind. The keratic muscles, so notably developed in
Cetacea, are feebly represented in Manatus; and the hyoepiglottidei of the former are
entirely wanting in the latter, as might have been expected from the condition of the
epiglottis.

The sterno-hyoid and sterno-thyroid are interblended. An omo-hyoid was not indis-

180 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

putably traced from origin to insertion; the anterior remnant remained, its posterior
fibres being lost among the tangled vessels and deep cervical fascia. Stylo-hyoid and
stylo-pharyngeus are somewhat adherent, the latter broad and well developed. The
digastric, single-bellied and broad anteriorly, fills the hollow at the inflection of the
mandible, and thence passes rearwards to the junction of the stylo-hyal with its cranial
cartilage. The horseshoe-shaped submaxillary gland abuts on its inner, and the parotid
on its outer margin. The stylo-glossus is large, and the constrictores superior and medius
are full and fleshy. The thin sheet of fibres of the levator palati cover the Eustachian
enlargement, and are spread out and lost in the posterior palate. The tensor palati,
better marked, arises near the tympanic bulla, passes round the pterygoid process, and,
by a strong flat tendon, widens out on the posterior palatal membrane. The pterygoidei
and plexuses lie outside. The palato-glossus is moderately broad, and the palato-
pharyngeus fairly developed. Mylo-hyoidei, as a thin fleshy plane, stretch and fill the
angle betwixt the ramal bodies. Long and thin genio-hyoidei pass from the basihyal
to the concavity of the chin, a vascular plexus existing beneath. A distinct hyo-glossus
was not observed; but genio-hyo-glossi and lingualis are both well represented.

VIII. Tot Nervous System.

When treating of the interior of the skull I dwelt upon the dura mater as it lines
the bones and the foramina piercing it basally. Its upper surface, when the calvarium
is removed, is tolerably smooth, a superior longitudinal sinus being but faintly indicated.
On each side the membrane is tucked into a deep Sylvian sulcus, which traverses well
across the cerebrum; another, marked but shallow, depression is manifest about the
centre of the posterior cerebral division. The dura mater is tough, strong, and rough at
the vascular sinuses and plexuses. While it is intact, the cerebrum leaves the bulging
cerebellum uncovered to a considerable extent.

The encephalon of the younger male was so destroyed as to be unfit for examination.
While the membranes surrounded the brain of the female specimen a tolerably accurate
idea of the cerebral contour was got; but on raising the dura mater the brain itself was
found to be softened, and with difficulty extracted. No measurements or weight were
taken, but the whole placed in spirit as rapidly as possible. A cast of the cranial
cavity with its enclosed dura mater was subsequently made; and by the help of this
cast and the shrunken brain the sketches (Pl. XXV.) were drawn.

I may remark, en passant, that the views (figs. 31 & 33) of the upper and under surface
of the brain slightly exaggerate the relative breadth of the anterior to the posterior
lobes, by the former not being approximate enough at the longitudinal fissure. With
regard to dimensions, the drawings are given as nearly as possible of the size of nature ;
the cranial interior, its model, and the preserved brain respectively yielding the scale
of relations. ;

From above and below, the outline of both cerebral hemispheres is somewhat qua-

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 181

drangular, but rounded at the corners; and the crescentic cerebellar posterior margin
lengthens this behind. The breadth to the cerebral length is absolutely great, but less
than in the Delphinide. In profile view the height of the cerebrum is nearly equal to
the length, and the figure, as a whole, remarkably Elephantine. The posterior cerebral
lobes cover but half of the cerebellum, thus leaving a considerable portion of the latter
free at the posterior end of the superior longitudinal fissure.

Four lobes may be distinguished, viz. frontal, parietal, occipital, and temporal. The
frontal lobe (/) is remarkably deep and perpendicular in direction, but of considerably
less diameter antero-posteriorly. Its orbital division fills the anterior fossa of the
cranial cavity; and its frontal part abuts against its anterior wall, the large olfactory
bulb being situated towards the lower end of the latter. ‘The parietal lobe (P), as
defined by cerebral anatomists, may be said in Wanatus to consist of two parts—to wit,
that anterior and that posterior to the deep transverse Sylvian fissure. The former is
a broad coronal band; the latter is a markedly three-sided area, occupying chiefly the
vertex, but also partially the lateral surface of the brain, and appears to represent the
angular lobule of some authors.

The occipital lobe (0) forms chiefly the rounded broad knuckle of the hinder surface
of the cerebrum, and is scooped out considerably below and mesially for the reception
of the cerebellum. The temporal (7), like the frontal lobe, is very deep, but of
smaller antero-posterior diameter than it, and not quite so perpendicular in its long
axis. In fact, it forms a thick, somewhat conical, mass which lies obliquely down-
wards and forwards, and occupies the wide sunken anterior area of the posterior fossa
of the skull’s basis.

The so-called central or median lobe, said to be of good size in the Elephant, I could
not differentiate in this Manatee, in consequence of the unsound condition of the
cerebral substance. Its existence, however, I cannot question.

The cerebral mass, as a whole, is fair-sized, full, and with very convex surfaces in all
directions. The hemispheres are divided by a deep, widish, great longitudinal fissure,
and each, moreover, possesses a most trenchant division into anterior and posterior half
by the Sylvian fissure.

As regards parts at the base of the encephalon, the pituitary body, when first
examined, appeared relatively large, was very vascular, flattish, and of a trefoil figure.
It occupied a greater area lengthwise and across than pi, figs. 33, 34, represent. The
transverse lozenge-shaped interpeduncular space, bounded by the optic tracts and crura
cerebri, is fair-sized. What appears as corpora albicantia, and possibly tubera cinerea,
are two antero-posterior, moderately large, oval eminences, situated in the middle of
the space, and behind and at the sides of these, respectively, distinct posterior and
anterior perforated spaces. Each crus (cr) is long, full, and prominent, and the two
diverge rather obliquely, not separating entirely till a short distance from the pons.
The pons Varolii (pv) is rather flat-surfaced, as, to a less degree, are the cerebral

182 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE,

peduncles; it is wide and crescentic, but moderately narrow from before backwards, and
the posterior border is slightly concave. The medulla oblongata is not remarkable for
size ; at least, like the pons, it is not prominent superficially at the anterior pyramids (ap);
and these have a very shallow longitudinal median depression. The olivary and restiform
bodies are individually well represented, though imperfectly defined in our drawing,
on account of the membrane having partially been left attached to the nerve-roots.

Of the cranial nerves I may remark that the olfactory root comes into view at the basal
end of the Sylvian fissure as a great, broad flattened tract. This narrows forwards and
then expands into a large pyriform bulb (1), which curves upwards and protrudes, as an
adpressed mass, against the antero-inferior surface of the frontal lobe. The optic
tracts (2), of moderate calibre, approach each other nearly transversely from the inner
borders of the so-called central lobes, and form a short, narrow commissure. The third
nerves (3) have a usual situation from the crural junction close to the pons, The
trochlear (fourth) nerve (4), a particularly fine filament, was but partially traced as it
wound round the right peduncle. Relatively and absolutely the fifth (5) nerve is of enor-
mous size, and, as it leaves the side of the pons, appears composed of a great number of
funiculi: but among these I did not discriminate its sensory and motor roots. The
flattened nerve passes sharply outwards and pierces the dura mater at the recess beneath
the posterior margin of the alisphenoid transverse band, where the Casserian ganglion is
lodged. The sixth nerve (6) appeared large, as certainly was the facial motor branch
of the seventh pair (7). The glossopharyngeal and pneumogastric branches of Willis’s
eighth pair of nerves (8), as also the hypoglossal or ninth nerve (9), issued as numerous
filamentous cords from the side of the medulla oblongata, and, unless from their more
anterior situation, undistinguishable from the spinal series. The different direction and
deeper situation of the spinal accessory branch (8*) of the eighth enabled it to be
distinguished with ease.

The interior of the brain I examined in two sections, viz. horizontally and vertically.
When the lateral ventricle is exposed, as in the left hemisphere (fig. 35), it is seen to
be a large chamber, and altogether spacious, The anterior cornu (ac), a sweeping semi-
' circle, is both deep and wide. The portion of the corpus striatum (cs) is a considerable
ovoid and prominent mass, leaving, however, a large cornual space in front. At its
posterior border, between it and the thalamus (¢/), the teenia semicircularis (fs), a narrow
linear strip, crosses it obliquely outwards and backwards.

The middle descending cornu (dc) is a moderate-sized cavity, with a more than usual
yertical curve in the usual directions. The eminence of the hippocampus major is very
proiinent, convex, and well defined; and continuing on to almost the tip of the tem-
poral lobe, it forms a not very distinctly notched pes hippocampi. A narrow fillet in
front I took to be a corpus fimbriatum. There is an undoubted posterior cornu (pc), a
fully developed hippocampus minor, and an eminence I am inclined to recognize as
eminentia collateralis.

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 185

The internal face of the encephalon, in longitudinal meso-vertical section, is shown
in fig. 34. In this view the body of the corpus callosum presents well-marked arching
from before backwards, being highest in front. It is of considerable depth throughout,
thickening very much as it sharply or subangularly bends downwards and backwards in
a prominent knee. This latter descends, moreover, by a rostrum of some magnitude,
which unites partially with the so-called “precommissural fibres”! of the body of the
fornix. The posterior or splenial end of the fornix increases very much in volume, and
terminates by a beaked process. At this point the returning commissural or ‘“ psalterial
fibres” of Flower’, which are shallow as compared with the splenium, pass horizontally
forwards and constitute the fornix. This latter augments in thickness and sweeps gently
down as its precommissural fibres trend towards and unite with the rostrum and genu
of the corpus callosum. Below their angle of junction is a circular connecting band,
the anterior commissure. This is of fair size, in this respect unlike that of the Porpoise
(Phocena), where Professor Huxley avers it is no more than 3/5 inch in diameter.

I regret, for many reasons, I have been unable to work out thoroughly the cerebral
convolutions of Manatus, as it would have formed a standard of comparison of the
Sirenian Order with the other Mammalia. At the same time my faulty material has
served as a sketch map sufficiently complete to recognize the type of folds. Whilst the
numerous secondary fissures and folds were in great part destroyed by the firm adhesion
of the pia mater, subsequent coalescence of the neighbouring walls, and scaling of the
cerebral substance superficially, yet I have been successful in elucidating the main sulci
and gyri. Thus, with other points, I offer more than a mere passing glimpse of the
structural organization of the brain of this remarkable group, and supply a desideratum
craved for by all biologists whose attention has been directed to their internal soft
structures.

As to fissures the main and most striking feature of each hemisphere is the great deep
Sylvian cleft (sy). On whichever face the brain is examined it is a conspicuous land-
mark, and cuts, as mentioned, each cerebral half into two well-defined areas, anterior
and posterior. Commencing at the middle lobe (island of Reil), on the brain’s base, the
Sylvian fissure sweeps round to the outer face and ascends almost perpendicularly half-
way up, then splits into an anterior and posterior division. For other fissures and gyri
consult the figures in Pl. XXYV. and their descriptions. I may remark of the brain as
a whole, that, in shape and type of gyri &c., it appears to follow more that of the
Elephant than those of Cetacea generally. Compared with the figure of the Dugong’s
brain, it is shorter, higher, and proportionally broader.

The pneumo-gastric nerve issues from the foramen lacerum, at its posterior part, close
to the rectus anticus minor. An inch below it sends upwards a laryngeal branch; and

1 Huxley, Hunterian Lectures, 1864.

2 «“Commissures of the Central Hemispheres of the Marsupialia and Monotremata,”’ Phil. Trans. 1865,
p. 634.

VOL. VIII.—PART 11. September, 1872. 25

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184 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

the main nerve goes down the neck, and on the right side crosses the subclavian artery
ere dipping into the thorax.

A descendens noni lies alongside the latter, and appears to issue from the same foramen.
It has a doubtful ganglion and a branch communicating with the pneumogastric, the
hollow of exit lying inside the stylo-hyal.

A hypoglossal nerve pierces the inner portion of the parotid gland, and passes forwards
and round the carotid artery lying upon the surface and inner border of the stylo-hyoid
muscle. There is a long recurrent laryngeal branch on each side.

The facial nerve is of large size, and escapes from the skull at the stylo-mastoid
foramen. It passes over the paramastoid process and the meshwork of vessels behind the
angle of the jaw, here piercing the substance of the parotid gland. It passes forwards
over both portions of the masseter muscle, and goes under the fossa of the downward
portion of the malar arch, where it is distributed on the surface of the buccinator and
other facial muscles.

The cervical and brachial plexus of nerves. In discussing the number of cervical
vertebrae, as opposed to De Blainville’s statement that there are seven, Stannius says’,
“TI counted also only seven pairs of cervical nerves; the strong phrenic nerve arises
from a bundle of the third and fourth cervical nerves, but it also receives a strongish
bundle from the second. The brachial plexus arises from bundles of the anterior
branches of the fifth, sixth, and seventh cervical and the first dorsal nerve; the bundles
of the sixth and seventh cervical nerves are thick and strong; but the fifth cervical and
first dorsal nerve are weak and thin.”

From the very elaborate reticular network of minute blood-vessels (which in the
male specimen I injected with tolerable success) I encountered some difficulty in traciig
the nerves issuing from the cervical foramina, but, with patience, I unravelled the inter-
woven tissues, and was rewarded with a fair view of them. Figs. 29 & 350 exhibit their
relations; but the first, or suboccipital twig, is hidden by the vascular rete in the latter
figure. The following are my notes of the dissection:—The first nerve, of small size,
comes out between the rectus lateralis and rectus anticus minor muscles and gives twigs
to them and the neighbouring parts. The second nerve, much thicker than the first,
issues between the atlas and axis, and crosses over the atloid attachment of the serratus
magnus muscle, and then over the lateralis to the anterior border of the shoulder, giving
branches to the suprascapular and other muscles in that region. The third cervical
nerve emerges between the second and third vertebra, posterior to the upper (larger)
tendon of the scalenus, but anterior to the diminutive additional tendon which is
inserted along with the larger into the axis—the same spoken of in discussing the
absent neck-vertebra. It divides into several filaments, and is distributed to the
shoulder-region like the second. Twigs connect the second and third and fourth
nerves. The fourth nerve, smaller than the second and third, but rather larger than

1 Op. cit. p. 8.

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 185

the first, has its exit from the same foramen as the third—namely, betwixt the second
and third cervical vertebre ; but it lies posterior to the tiny second tendon of the
scalenus. It joins outwardly the fifth nerve. The above four roots may be regarded
as constituting the cervical plexus.

Of the nerves forming the brachial plexus, the fifth is of considerable calibre, and
issues between the scalene tendons, marking the third and fourth cervical vertebre.
After a short course it joins the sixth nerve, From this union a broad nervous cord is
derived, which proceeds to the shoulder, dividing into several branchlets, which supply
the inner surface of the supraspinatus, &c. The sixth nervous trunk comes from the
intervertebral foramen, between the fourth and fifth cervicals. It is a thick, flat cord,
compared with the others, and joins, as aforesaid, the preceding fifth nerve.

The seventh nerve, a large cord at first, is situated between the fifth and the sixth
cervical vertebra, and has the vertebral artery lying above it.

Lastly, the eighth cervical nerve, counting from before backwards, has exit from the
foramen immediately above the first rib and between what appears to constitute the
sixth cervical vertebra and the first dorsal. The two nerves, seventh and eighth, con-
tinue outwards parallel to each other, deeper than but immediately anterior to the
arch of the axillary artery. A twig from the chest or costal nerve joins the last on
the scalenus muscle above the rib.

The phrenic nerve, as already intimated, does not come either from the third or
fourth branch of the cervical plexus, but instead appears to be the continuation of
the bridge of junction betwixt the fifth and sixth. It leaves the latter with an outward
flexure, being fastened by a loop of the cervico-axillary fascia over the artery, which may
represent a thyroid axis. The nerve proceeds towards the chest, and enters it over the
first rib, close to where the axillary artery is derived. What I presume to be the long
thoracic is derived from the seventh and eighth nerves, and traverses the chest super-
ficially to the enlarged lymphatics of the axilla, encompassed at first by the rete
mirabile and further on lying upon the surface of the mammary gland.

The dense mass of vessels matted to the brachial nerves prevented the composition of
the primary cords being efficiently noted; but some of their tracks lower down were
easier to follow. The median nerve, of moderate thickness, goes below the pronator
radii teres, then on the flexor primi internodii pollicis, &c. to the wrist, underlying the
flexor communis. Distally it splits into three branches, with subdivisions to the digits.
The anterior interosseal division keeps company to beyond the pronator, thence, lying
on the interosseous ligament, proceeds to the wrist and splits into twigs. A branch,
apparently from the median, leaves it above the elbow-joint, runs to the brachialis
anticus and distributes other twigs to the cubital joint and neighbouring parts. The
musculo-spiral, a large thick cord, before reaching the humerus, splits into funiculi,
part of which enter the triceps, brachialis anticus, &c. The radial nerve passes along-
side the latter muscle, then beneath the pronator, and along the radius to the root of

28 2

186 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATER.

the indicial and second digits. Twigs from it, moreover, supply the parts at the wrist-
joint. About the head of the radius the posterior interosseous division from the radial
takes a course along that bone. The ulnar nerve on reaching the inside of the olecranon,
thereafter divides into three. A large cord goes to the root of the fifth digit and supplies
the parts on it and the fourth. The second, also a thick cord, is imbedded within the
dorsal aspect of the palmaris and flexor carpi ulnaris muscles, accompanying them to
the pollicial metacarpal, and then breaks up on the same. The third division is mus-
cular, chiefly devoted to the palmaris and flexor ulnaris.

IX. Sensory ORGANS.
1. Nose and Nasal Passages.

The Sirenia differ very materially from the Whale tribe in the form,'structure, and
general nature of the nasal organs. Neither has their nose close outward resemblance
to the great nasal trunk of Proboscidea, nor even to the more curtailed appendage of
the Tapiride. In fact, it might as deftly be compared to the snout of the Suide as
either of these, though, strictly speaking, it is unlike either. The great furrowed and
bristle-clad semilunar upper lip and truncate snout of Wanatus have been fully described
by preceding writers; and each notes the pair of narial orifices on the top of this, just
as it shelves to the perpendicular. This position of the nares is a seeming rather than
real approach to the type of Cetacea, yet altogether dissimilar. Examination shows
that were the trunk of an Elephant cut short at the root, or, better still, left entire, but
contracted to a minimum of its long diameter, and with the terminal tactile appendage
aborted, structurally the Manatee’s naso-labial organ would assimilate with it.

The nasal and facial muscles I have described and compared with those of Elephant
and Whale in the chapter on the myology, and, before treating of the interior nares,
repeat that there are no appendicular sacs whatsoever as in the latter marine form.

The nasal cartilages are very simple. There is a thick septal cartilage (sp, fig. 38,
Pl. XXVI.), the continuation of the vomerine rostrum, and which fills the grooved canal
on the floor of the nares. It slopes down from the anterior mesial edge of the frontal
bones to the proximal part of the osseous premaxillary rostrum, where it stops short.

Upper lateral and alar cartilages cannot be separated ; but what represents the former
or both (nc) is a superior cartilaginous narial roof or outfolding of the septum. On
each side this covers the large anterior narial vacuity or chamber (n.ch, fig. 37) in a
convex manner, being fastened to the bone exteriorly from the frontal along the
inferior inner edge of the nasal and premaxillary to the root of its rostrum. On
nearing the latter point it splits; or its mesial portion, that in connexion with its fellow
of the opposite side, continues as a splint along with the septal cartilage forwards, and
is separated from the outer fork by a long and narrow oblique fissure (cf. fig. 38).

The two anterior cartilaginous fissures, as looked at from above, have an acute
V-figure, and fall short of the outer nares, the nasal passages being continued forwards

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 187

from them by narrow canals, each nearly a couple of inches long, and which open by
two crescentic horizontally placed orifices on the summit of the truncated snout. Each
narrow anterior canal, and its terminal crescentic narial orifice, are surrounded by and
perfectly under the control of the powerful nasal muscles already detailed. The
auterior nares are situated about half an inch apart from each other (rather less in the
young male), and they individually have about as much vertical and transverse diameter
when dilated. When contracted they appear simply flattened semilunar transverse slits
at the top of the corrugated fleshy snout.

The olfactory passages may conveniently be regarded in the Manatee as consisting
each of three compartments. Behind is the postnarial chamber, partially divided in
front from its fellow of the opposite side by the vomer and septal cartilage. Below, it
is wide and somewhat tubular; above, it is narrowed and outwardly curved, or follows
the outline of the turbinal, thus forming a lower and an upper meatus.

In advance of the postnares, and without any decided constriction from the posterior,
is the median narial chamber (n.ch, fig. 37), namely that portion covered by the nasal
cartilages. In front this is very narrow; and its floor forms a kind of cul de sac just
behind the prominent premaxillary rostrum, above which, or at its top, is the narrow
cartilaginous opening already spoken of. From this point forwards is the anterior
compartment, or narrow tubular passage heretofore described.

A highly vascular layer of Schneiderian membrane lines the two so-called posterior
nasal chambers; but as it reaches the anterior canal it assumes more of the character of
an ordinary mucous membrane, and at the semilunar nasal orifice is livid, and apparent
less delicate and sensitive than are the internal chambers.

As regards the sense of smell possessed by Manatus, I am not aware it is gifted with
delicate olfactory perception; at least I do not know of any observations on the living
animal to substantiate such an assertion. If, however, size of olfactory bulb tally with
the function of smell, this faculty is far from deficient.

2. Ocular and Auditory Apparatus.

Compared with the orbital cavity the eye is most diminutive; around it, however,
are fatty tissues, a manifest vascular rete, a great bunch of infraorbital nerves, &c.; so
that the space is well packed. Divested of adventitious structures, the ball of the eye
has a diameter a trifle over half an inch, and is nearly spherical. The pupil, as far as
I could judge, inclines to a transverse oval, and is less than 0-2 inch in diameter. The
crystalline lens is proportionally small, and with an antero-posterior compression. Ante-
riorly the sclerotic thins, but posteriorly (as in Cetacea) is relatively very thick and
dense. The convexity of the cornea is but moderately protuberant, the aqueous chamber
therefore small or perpendicularly high; the vitreous chamber also has a vertical dia-
meter greatly in excess of its horizontal one. Ciliary processes are abundant, and
furnished with pigmentum nigrum ; and the tapetum, though lighter in hue, neverthe-
less has a delicate choroidal layer of pigmentary matter. A third eyelid or nictitating

188 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

membrane is present; to this, as in the Elephant, a cartilage is attached; and the chief
opening of what represents a Harderian duct is at a recess below the inner middle of
the lid. A lachrymal gland was not distinguished. ‘The choanoid muscle is divided
into an upper and a lower pair of strong bands; and the superior inner one, with an
oblique course, has a partial attachment to the cartilage. The antagonist to this is the
levator palpebree, a narrower slip, obliquely directed inwards and downwards from the
tarsal membrane. ‘The remaining orbital muscles are much weaker, and posteriorly are
lost in the dense sheath of the long optic nerve. Taken as a whole the eye is very
elephantine, yet combining, in thickness of sclerotic, outline of chambers, rete, &c.,
whale-like characters.

In the absence of pinna a small orifice, a line in diameter, into which a probe could
be passed, alone represents the external meatus. It is situated on a level with the
posterior end of the malar bone, 4 inches behind the eye. A narrow cord-like fibrous
tube, 3 inches long, with an S-shaped bend, leads to the membrana tympani. The
latter is a wide ellipsoidal thickish membrane, the fibres of which from above and
below obliquely meet the tube as it passes across the centre. <A thin narrow edge of
the malleus abuts against the inside of the membrane in the same oblique direction,
and divides the tympanic cavity into an upper and a lower chamber. ‘The swollen
malleolar head rests in the anterior cavity of the periotic; and, with a tricuspid facet,
the much smaller but wide-limbed incus is attached superiorly and posteriorly to it.
The fork of the incus embraces a descending process of the posterior half of the periotic ;
and the shorter incudal limb articulates with the stapes. ‘The latter, a nearly solid,
straight bone, inferiorly rests in a groove of the petrous portion of the periotic. In
both instances none of the small ear-bones was ankylosed to the tympano-periotic.
The large Eustachian tube communicates with the auditory chamber just in front of
the stylo-hyal cartilage. I was disappointed of further examination of the interior soft
structures, the injection having extravasated in the one case, and necessity for destruc-
tion of the bones interfering in the other.

X. Parts RELATED TO GENERATION
(in the Female and Male).

In Sir Everard Home’s figure, copied by Frederick Cuvier and others, a very pro-
minent teat is represented as occupying the postaxillary space. This was not the case
in either of the Society’s specimens, most probably from their juvenile condition,
although it is to be remarked that the larger one equalled Sir Everard’s in size. The
female, however, had a pair of rudimentary axillary nipple-like bodies; but in the male
none were found. On removal of the integument in both animals, a careful dissection
was made of the subcutaneous tissues and the fat filling the deep interspace between
the shoulder and pectoral portions of the panniculus, but no trace of lactiferous ducts
could be detected.

Upon the surface of the chest, immediately behind and partially dipping into the

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 189

axillary space, was a moderate-sized semidivided glandular mass, lying between the
tips of the first and second ribs and the inner border of the latissimus. This exhibited
structure more resembling enlarged lymphatic glands than a mammary organ. Part of
the mass doubtless belonged to the lymphatic system; but that portion of it which
appeared to constitute the mammary gland lay upon the scalenus muscle, between the
most anterior digitation of the external oblique and the middle of the first rib. The
outer border of the pectorales muscles partially overlapped it; the latissimus, as said,
formed its outer boundary; and the panniculus was superincumbent. The lymphatic
portion, which dipped into the axilla, was surrounded by a rete mirabile; but that
portion which, from position, I took to be the mammary gland, had no such envelope.

The position of the generative outlet is mentioned in the paragraph of measurements.
Excepting in proximity to the anus, there is really very little difference between the
sexes. An elevated labial rim surrounds the vulva, diminishing behind as it passes into
a linear perineal raphe. A few shallow sulci le on either side of the latter. The
clitoris, hidden in the anterior fork, is large and rough, resembling much the prepuce
of the male. The vagina, during adolescence, is short, wide, and rugous, the os tince
large and prominent. The body of the uterus, lengthened, narrow, and with many
longitudinal mucous folds, divides above into right and left cornua, the outer extremities
of which contain the ovary and fimbriated extremity lodged in the hypogastric fossa at
the hinder end of the diaphragm.

Each renal organ in our female is 5 inches long, the two lying opposite one another.
Their figure is simple, with only a superficial indication of lobulation, but in reality
absence of division; hilus shallow. The kidneys rest upon the tendinous surface of the
diaphragm, close to the spine, the posterior ends reaching the last ribs. The ureter
uniform in calibre in its course to the semiglobular bladder, hooks round the uterine
cornu and beneath the hypogastric artery (fig. 50), finally piercing the base behind
the neck.

As regards the male sexual parts I have little to add to Vrolik’s excellent figures and
description. On comparing figs. 47 and 48 a considerable resemblance between the
glans penis and clitoris is apparent, the meatus urinarius of the male being slightly
elongate. The correspondence, again, in general appearance, position, &c. of the testes
and spermatic duct with the ovaries and cornua is not a little remarkable; and this is
even more heightened by the presence of a hypogastric fossa (Af, fig. 49) and rete
mirabile in the neighbourhood.

XI. Rank anp ReELAtTiIons oF MANATUS.

It was a most natural conclusion of the earlier naturalists to look upon the Lamatins
as modified Whales (Cuvier’s Herbivorous Cetacea), still bolder of De Blainville to
class them as aberrant Elephants (Gravigrades), but more just and safer of [liger to
group them apart as an order Sirenia. Every animal doubtless has its appointed place
and time in the great scheme of creation, Could we but for a moment remove that

190 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

misty film which here and there drapes some with tantalizing indefiniteness (leaving
them like islands and peninsulas, sea-girt, or but narrowly connected to the, so to say,
mainland of typical forms), we should be astonished, and bow in reverence to that fiat
which has planned and carried out such a grand design. Probed to its entirety and
ramifying links, each vertebrate might yield a life’s study; but the more fascinating
to biologists of all times have been those strange and uncouth types, leading to all
manner of fanciful conjectures. MJanatus and its kindred are among those piquant
forms, fit food for speculation. Is it a retrograde, dwarfed, or undeveloped Elephant ?
a “‘true embryonic type of Pachyderms,” as the elder Agassiz’ puts it. Is it a partially
converted Cetos? Is it the reflex of unknown and antedated swarms of mammals of
intermediate organization, which would fill up the chasms of structural differentiation
yielding lines of demarcation to modern systematists? Such interrogations, to be
answered satisfactorily, require a more comprehensive knowledge of the embryology
of Pachyderms and Cetacea, a far greater acquaintance with allied fossil forms, a
better appreciation of what constitute transitional links, and a further profound
investigation into the principles of the doctrine of evolution. These gaps in science
necessarily limit generalization, and cause reply to be theoretical. The most that can
solidly be affirmed is that Manatus and three other genera sufficiently differ from other
known mammals, so that under the present aspect of classification they best constitute
in themselves a separate order, Sirenia. The Sirenia, however, gradate into extremes,
or rather may be tabulated thus :—

CErrAcEA R Hi

hytina. SrRENIA. alitherium. PACHYDERMATA.

According, therefore, as we contemplate either end of the lozenge-shaped area does
the consanguinity of the Sirenia trend towards marine or land animals. Manatus, in
the totality of its characters, tends more towards Pachydermata than Cetacea; but
in its individuality we cannot strictly say it belongs to either, or predict its being
an embryonic type of the former. Between each two of the three above orders are
wide intervals. Still, with our scanty knowledge of paleontology, remnants of animals
are revealed, combining characters which we are apt to consider appertain but to one.
Moreover the relations of the Sirenia are not solely bound by the two orders given,
although these seem more direct in their affinities. Such aberrant types as T'richechus,
Zeuglodon, &c. point to other radial lines of alliances. The labours of the veteran
Professor J. F. Brandt, in his “Symbol Sirenologice,” are most copious in com-
parisons of the like kind; but with all his conclusions as regards Manatus and its
allies I do not coincide. The above diagrammatic view I believe expresses the probable
kinship of the Sirenian genera one to the other; but to give full reasons therefore would

Proc. Bost. Soc. Nat. Hist. 1848-51, p. 209.

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 191

entail my entering on data which I reserve for another communication. Brandt forms
one family, Manatidie, containing the genus Manatus, and a second, Halicoride, with
three genera, Halitherium, Halicore, and Rhytina. Excluding Halitherium, not noted
by him, Dr. Gray’ ranges the others under the family Manatide. Professor Kaup’s”
generalizations I reserve till I treat of Halitherium.

Tam aware I tread on tender ground, and may evoke the contumely of those who
see every group with noonday light, clear and circumscribed, when with others I suggest
demolition of boundary lines by upraising past forms to take their place in the alphabet
of Zoology. But, however beneficial classification may be to the study of animals, there
is a still higher aim when we would discard pretension to system, and strive by patient
research to fathom the intricacies of creative organization.

The more important additions to the anatomy of the Manatee contained in this
memoir are:—accurate representations of its figure; fresh views of exterior moot
points; the peculiar nature of the epidermis; structure of the hairs and bristles; the
vertebral irregularities, which cervical is the one missing ? the skull’s interior, its develop-
ment; the ligamentous system; entire myology, the limb-muscles being fully developed ;
the homologies of the mouth-structures with reference to baleen &c.; revision and
illustrations of the digestive organs and associated glands ; new sectional views of the
body, with organs in position; reexamination and depicting of the remarkable vascular
distribution ; parts connected with respiration and vocalization; the brain, not before
known ; elucidation of the nerves; the nasal passages and the eye; illustration of the
female generative parts and lumbo-pelvic regions.

XII. AppitionaL Note.

The Zoological Society of London is so much indebted to its correspondents and other
kind friends, that I cannot pass in silence the efforts made in this case to ensure safe
transmission of what has long been a desideratum. The exhibition of a live specimen
of the order Sirenia (a veritable mermaid) in the Regent’s-Park collection would, if
achieved, form one of the most sensational triumphs incident to the introduction of
rare and comparatively unknown animals into Britain. But the chapter of travelling-
accidents is a tangled one. Safe transport of living large marine animals, even under
the most favourable circumstances, is a task requiring sound judgment and much tact.
Moreover obstacles increase proportionally where the clime is different, the distance
great, or the place of capture far removed from ready mechanical appliances and
abundant manual assistance. In the present instance it may be affirmed that success
in a most difficult undertaking was twice well nigh accomplished.

After many endeavours and promises of reward, Mr. George Latimer. of Porto Rico,
in 1866 had the good fortune to obtain from some fishermen a young female Manatee
which they had caught in one of the neighbouring “ corals.” The natives, it seems,

' B. M. Cat. of Seals and Whales. > Beitriige, d. urweltlichen Siiugethiere, 1855.

VOL. VIII.—PART Ul. September, 1872. 2F

192 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

after having captured the creature, fastened a rope round the narrow end of its tail, and
thus detained it as a prisoner in the water for some weeks. As soon as it came into
the possession of Mr. Latimer, a large tank, some ten feet long and several feet deep,
was prepared. Animal and tank were shortly afterwards despatched for England, widé
St. Thomas, and per Mail Steamers ‘Conway’ and ‘Tasmanian.’ Mr. Latimer’s very
handsome presentation to the Society, however, was not destined to survive the confine-
ment and the angry surge of the Atlantic. Both Captain Hammach and Captain
Sawyer, of the above steamers respectively, were much interested in the safe transit of
this negro Siren. The latter gentleman, indeed, with true sailor-like generosity and
care for the well-being of the creature, on finding the motion of the vessel injurious to
it, caused the tank to be lessened, well padded, and slung fore and aft to prevent the
Mermaid being rolled about toomuch. Notwithstanding these precautionary measures,
several days’ very rough weather had a prejudicial effect, and cutaneous abrasions re-
sulted. Meantime it fed badly. Whether from this cause, from the rapid spreading
of the skin-ulcers, or from a sudden change to very cold weather, the Manatee quickly
succumbed, and died early on the morning of the 24th March, namely ten days after
leaving Porto Rico, and seven from St. Thomas.

The body was disembowelled, filled with salt, and placed in a corner of the ice-house.
The entrails were partially cut up and preserved in spirit. In this manner the carcass
reached me in tolerably sound condition, the brain alone being rather soft.

Whilst Mr. Latimer was striving to obtain a Manatee for the Society, another corre-
spondent, Herr A. Kappler, of Surinam, was likewise bestirring himself to procure one.
Indeed, ere the former gentleman’s letters and animal had arrived, our Superintendent’s
son, Mr. Clarence Bartlett, was on his way out to bring home a young male Manatee
from Herr Kappler. This specimen had been captured in the Maroni river, and
confined in a creek, an offshoot of the main stream. The mother of this suckling had
been killed (the same I have mentioned as now lodged in the Stuttgart Museum), and
the youngster transferred to the small sheet of water, where it was duly fed with cow’s
milk. A few months passed ere Mr. Bartlett had all ready for a start; for great
difficulty was experienced in preparing a water-tight tank in that outlandish country,
where carpenters were scarce, the wood as hard as iron, and zinc or tin a rare com-
modity. During this interval, however, ‘‘ Patchly” (for so the creature was christened)
became tolerably tame, and sucked milk freely from a bottle.

On the 19th of June Herr Kappler and Bartlett started en route, but nearly lost
their charge; for on traversing a dangerous current of the Maroni river the boat, with
the great awkward tank lashed to it, all but upset. Reaching Paramaribo, two days’
journey from Mr. Kappler’s dwelling, this courteous gentleman returned, and Bartlett
came on in a Dutch steamer to Demerara. But the danger was not past, as a hurricane
well nigh swept tank and Manatee overboard. On the 25th of the month Barbadoes was
reached, and on the 29th St. Thomas. Up to the 8th July every thing bade fair that

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 193

the Manatee would survive the voyage. It had a supply of fresh goat’s milk every day, and
occasionally a banana. On the 9th a chilling north-east wind set in, and the Manatee
took suddenly ill, and died the next day, just within two days’ sail of Southampton.

Thus, unfortunately, was the second attempt to fetch a live Manatus to England
frustrated.

Before concluding, I shall for a moment glance at the practical points which the
reverses above met with teach.

Ist. It seems a necessity that such an animal as the tropical Manatee should be
conveyed to our climate only during very fine summer weather. A month later or a
more favourable season might have saved the young male.

2nd. It is very essential that in the event of injuries or rough treatment being
inflicted during capture, some time should elapse before shipment, so that recovery take
place prior to transport. Had the dermal wounds of the above female healed before
removal, it would have augured better for its safe carriage.

3rd. The size of the animal being roughly known, it behoves that a well-constructed
receptacle be prepared beforehand, either in England or some large town where proper
material and workmanship are obtainable. This should be strong, but also as light as
possible, and with rings or clasps so fixed that the tank could be hoisted or shifted
about easily.

4th. Neither too great depth nor length are desirable, as the swaying motion of a
vessel so jolts the water and animal about, that injury to the latter is sure to be
sustained.

5th. As Mr. Greey, late purser of the S.S. ‘Tasmanian,’ justly observed, the body in
part and the tail might with benefit be encased in blankets to prevent cutaneous
excoriations. And if the creature were partially slung hammock-fashion in the tank,
there would be less danger of knocks and abrasions.

6th. It is important that the tank be placed in that part of the vessel least subject
to oscillation, and lengthwise fore and aft.

7th. A covered tank is preferable to an open one—as curious visitors are sure to
poke the animal about, in the event of those in charge being absent.

8th. Fresh and sufficient supply of wholesome food should be provided; and due
cleanliness attended to, without disturbing the creature too frequently.

Finally, it is to be remembered that, although unsuccessful in the two above attempts
to transport a Manatee to the Society’s Gardens, the efforts have not been entirely
fruitless. So much experience has now been gained how to manage the difficulties
that the whole matter depends on another determined attempt.

I trust, therefore, such an interesting form as Manatus, and one which at no iar
distant period will be reckoned among mammals of the past, may yet ere too late
become a denizen of the Society’s Gardens.

2F2

194

Fig.

Fig.

Fig.

Fig.

Fig.

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

DESCRIPTION OF THE PLATES.

PLATE XVII

. Lateral view of the body of the young male Surinam Manatee (Janatus

americanus, Cuv.) forwarded to the Society by Herr A. Kappler. Photo-
graphed from the dead body, 3 natural size. The tail is seen, not in profile,
but slightly tilted towards the observer. n, nasal orifice of the right side ;
c, tail-cleft.

. Abdominal surface of the same animal, also from a photograph: w, umbilical

cicatrix ; p, external orifice of the penis; @, anus.

PLATE oy lit.

. Dorsal aspect of the body, the pectoral limbs (as in fig. 2) being outstretched.

+ the size of nature, and from a photograph. 1, nares; @, eye.

. Pectoral limb of the left side, seen on its external surface, photographed its

natural dimensions. J, LJ, IIT, first, second, and third digital nails.

PLATE XIX.

. Head and neck, as far as the shoulder, of the same young male Manatus.

From a photograph, corresponding as near as possible to the natural size of
the animal. n, left nose-opening; ea, ear-hole, or orifice of auditory canal.

PLATE XX.

. Front, and consequently fore-shortened view of the head, body, and pectoral

extremities of the above specimen. Reduced in size from nature. The
body lying on a table while being photographed has necessarily slightly
flattened the chest. e, eye; , narial orifice.

. Muzzle with the mouth opened, from a photograph, of the natural size,

showing :—nn, narial orifices; also the upper and lower lips (outer), the
palatal or upper pad, and the mandibular or lower pad (=the additional
labial masses, or inner, extra upper, and lower lips of some writers).

PLATE XXI.

. Side view of the female Manatee, + natural size, with skin and subcutaneous

fat removed, exposing the superficial muscular layers. The broad tail, con-
sisting of fibroid and dermal tissues, is necessarily absent.

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

195

Muscles of the Body and Tait.

Sp.d. Spinalis dorsit+-Levator caudee in-
ternus, Lei.

L.d. Longissimus dorsi-+Levator caude
externus, Lice.

Sp. Splenius; Co. Complexus.

Tz. Trapezius; Rh. Rhomboideus.

SS

ki. External intercostals.

E.o. External oblique.

Sacro-lumbalis.

Lcd. Lumbo-caudalis.
Se. Sacro-coccygeus.

P.c'.\ Different portions of the panniculus
P.c’. | carnosus muscle; including the
P.c. | platysma myoides, or transverse
Pigs nuchal portion of the panniculus.

La.d. Latissimus dorsi.
ff Dorsal layer of fat.

Muscles of the Head.

Te. Temporalis; ae. Auditory canal.

O.p. Orbicularis palpebarum.

L.j.s.a.n. Levator labii superioris aleequee
nasi.

L.s.p. Levator labii superioris proprius.
D.1.i, D.1.i*. Depressor labii inferioris.
D.a.0. Depressor anguli oris.

Pe’. Mandibular portions of panniculus.

Muscles of the Pectoral Limb.

Isp. Infraspinatus.

D. Deltoid.

1", T°. Triceps (first and second portions).
T.ma. Teres major.

B.a. Brachialis anticus.

L.md. Extensor minimi digiti.

|

Pi ke.
S/.¢E.c.r./. Supinator longus and extensor
carpi radialis longior.

Palmaris longus &c.

F.c.d. Extensor communis digitorum.
E.c.u. Extensor carpi ulnaris.
E.p.i.p. Extensor primi internodii pollicis.

Fig. 9. Under surface, showing the oe muscular layer of the right half of the

body, and dissected deeper parts of the left moiety.

The letters used in

fig. 8 are applicable to similar parts exposed or cut short in the ventral

aspect.
covered.

R.ab. Rectus abdominis.

£.o. External oblique.

I.o. Internal oblique.

Tra. 'Transversalis.

Is.c. Ischio-coccygeus.

Ifc. Tnfracoccygeus.

P.ma, Pma*. Pectoralis major.

P.mi.
A, anus; V, vulva; Pl, pelvic bone;

Pectoralis minor.

C and J, carotid artery and jugular vein;

The following muscles, vessels,

&c., besides are seen partly un-
C.h. Cephalo-humeral.

St.m. Sterno-mastoid.

S.hy. Sterno-hyoid and Sterno-thyroid.
Thy. Thyro-hyoid.

S. Subscapularis.

Di.
Ma.
TH

Digastric.
Masseter.
Levator labii inferioris.

Ab. Rete, mammary arteries as a rete mirabile;

Axv.Rete, axillary plexus of vessels; ¢7,

trachea; M/.g/, mammary gland; P.g/, parotid gland; Sz.gl, submaxillary gland.

196 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

Fig. 10. Second layer of the muscles of the head, with portions of the panniculus cut
short to show their cranial insertions.

Te. Temporalis.

Di. Digastric, seen in part.

Ma', Ma’. Masseter, two layers.

L.l.s.an. The
aleeque nasi cut short and reflected.

levator labii superioris

L.s.p. Levator labii superioris proprius.
Cn. Compressor nasi &c.

0.0. Orbicularis oris.

Bu. Buccinator.

D.a.o. Depressor anguli oris.

D.1.. Depressor labii inferioris.

Pe', Pe’, Pc’. Cheek and lip insertions of

panniculus.

Px, Vascular plexus emerging from skull behind the mandibular condyle.

Fig. 11. Third and deepest layer of cranial muscles as viewed in profile. The same

lettering is used as in the preceding.

muscle ; Ty, tympanic bulla.

Fig. 12. Muscles of face and muzzle seen from above.

Z, zygomaticus; Md, Mandibularis

On the right side the levator

Fig. 13. Pectoral limb, inner view.

labii superioris aleeque nasi has been entirely removed, the dotted line
indicating its outline. On the left side the levator labii superioris proprius
and maxillary portion of panniculus have been dissected, cut short, and
Additional letters are:—/Pn, Pyramidalis nasi; and Pa,

infraorbital plexus of nerves, &c.

thrown forwards.

PLATE XXII.

The upper layer of the forearm muscles in place,
and insertions into scapula and humerus of some of the thoracic ones dis-
Rh, rhomboideus; S.mg, serratus magnus; Timadé La.d, teres
major and latissimus dorsi; P.ma &P.mi, pectorales major and minor;
L.cl &C.h, levator clavicule and cephalo-humeral; B'd-B’, biceps, first and
second heads; Z", 7’, 7", triceps, three bellies; B.a, brachialis anticus ;
P.y.t, pronator radii teres; cr, flexor carpi radialis; F.c.d, belly and
palmar distribution of the common flexor of the digits; F.c.u, flexor carpi
ulnaris ; 7, palmaris longus; Ab.m.d & Fb.m.d, abductor and flexor brevis
minimi digiti; Pe, aponeurosis from panniculus.

played.

ig. 14. Upper layer, short palmar muscles. Letters as in preceding. J’, superficial

interossei; 1 to 5, the digits.

Fig. 15. A similar view, but with the superficial muscular expanse (J*) hooked forwards,

exposing deep interossei: Jd, deep interosseous series.

Fig. 16. Profile foetal skull of Manatee in the Amsterdam Museum. Nat. size. Fr,

frontal ; Ma, maxillary; Pmx, premaxillary ; Pa, parietal ; So, supraoccipital ;
Sq, squamosal; Ju, jugal, and S an adjoining sesamoid bone; Ty, tympanic;
Md, mandible. The dotted line indicates continuance of ascending contour,

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. PIF.

and 1, 2, 3, separate ossific centres; fo'dé fo, the parietal and occipital fonta-
nelles; O, orbit; Mf, mental foramen.

Fig. 17. Base of the same, additional lettering as follows :—Bs, basisphenoid ; As, ali-
sphenoid; Os, orbito-sphenoid; P/, palatine ; Bo, basioccipital ; Ho, exoc-
cipital ; fm, foramen magnum ; Hus, Eustachian sac; Sf, sphenoidal foramen ;
Jof, infraorbital foramen; An, anterior palatine foramen; J, incisor-cavity ;
Mo, molars in dental sacs.

Fig. 18. Mouth view of the partially dissected lower jaw with tongue, larynx, hyoid,
and muscles in situ. The dotted lines respectively show the approximate
limits of the so-called outer lips (consult fig. 7 &c.).

b, bristles on 7/, lower lip; sp, spines on Jp, lower mandibular or symphysial pad;
T, tongue; id, inferior dental foramen; @, cesophagus; ¢7, trachea; Cs, constrictor
superior; Cm, constrictor medius; S.ph, stylo-pharyngeus; Stg+-h, stylo-glossus and
hyoid.

Fig. 19. The palate and portion of the upper lip of the same female Manatee. The

dotted lines indicate the contour of the muzzle &c. (see fig. 7).

ul, wpper lip partly in outline; wp, upper callous pad =inner upper lip; 3, bristles;

sp, palatine spines; 0h, buccal or inner labial hairs.

PLATE XXIII.

Fig. 20. Reduced sketch of the viscera im situ of the young male Manatee. The lower
left lobe of the liver is partially dragged out by a hook, the better to expose
the natural forward tilt of the great curvature of the stomach.

I& IV, first and fourth gastric cavities; and J/J, placed on liver, points to the third semi-
spiral appendicular cavity; g/, cardiac gland; sp, spleen; Cw, at root of bifurcate
cecum ; 7, right, and /, left, duplex lobes of liver; G6, gall-bladder ; pe, pericardium ;
H, four cavities of heart; pa, pulmonary artery; ao, aorta; w, umbilicus; p, aper-
ture for penis; @, anus.

Fig. 21. The compound stomach, sliced open to show cavities and wall-structure.

@, cesophagus; J, first gastric cavity (* and white arrow indicate its upper sacculus) ;
gl, cardiac gland; JJ, second cornual cavity; JV, fourth cavity; d, duodenum ;
1, eesophageal opening into stomach; 2, stylet entering orifice of cardiac gland;
3, communication between J & JV stomachs; 4 & 5, two stylets passing respectively
into the JJ & IIZ cornual gastric divisions; 6, pyloric orifice; dch and pd, ductus
communis choledochus and pancreatic duct, to the orifices of which arrows also
point; m, gizzard-like thickening of muscular coat.

Fig. 22. Compound stomach, denuded of its serous coat, and exhibiting the direction of
the external layer of muscular fibres. Lettering corresponds with fig. 21.

198 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

Fig. 23. Semidiagrammatic view of stomach as it appears on the cesophageal or upper
surface.
Fig. 24. A transverse section, about the middle of the cardiac glandular appendage,
showing its irregular diverticulate central cavity and surrounding gland-cells.
Fig. 25. Piece of the small intestine, towards the duodenal end, showing form of ruge
and P, Peyer’s glands.
Fig. 26. Ditto, from the ileum, with glands (Z) or crypts of Lieberkiihn? m, muscular
coat.
Fig. 27. Portion of gut from near the rectum: JZ, glands, as above.
Fig. 28..Tleo-colic segment of the intestine, sliced open to show interior structure.
a, ileum ; c, colon, * its enlarged commencement; Coe’, exterior, and Coe’, interior of
the cecal appendages; g/, compound and sacculate ileo-colic valve-gland; m, thick-
ening of muscular coat, the valve’s wall.

PLATE XXIV.

Fig. 29. Short deep muscles of the ventral surface of the neck; intervertebral exit of
the cervical and brachial plexus of nerves, and membranous chambers, postero-
base of skull. Right side with upper layer and a partial outline of shoulder ;
left moiety, deeper view, and opened basicephalic chamber.

R.a.ma. Rectus capitis anticus major. S.mg. Insertion of serratus magnus into
R.ami. Rectus capitis anticus minor. Ch. Cephalo-humeral. [atlas.
Lc’, Le’, Le’. Longus colli, its three parts. St.m. Tendinous insertion, sterno-mastoid.
il. Rectus lateralis. Sih. Stylo-hyoid cartilage, cut cranial
Sca. Scalenus. origin.

1, 2, 5, 4, 5, 6, 7, & 8, anterior spinal cervical nerves issuing from the intervertebral
foramina; Ph, phrenic nerve; Mn, facial nerve at exit; na, posterior nares; ptp,
pterygoid process; Hus, Kustachian sac, opened on left side.

Fig. 30. Anterior segment of the body, with the limbs cut short. Dissected so as to
lay bare chiefly the heart, main vascular trunks, and complex rete mirabile of
the neck and upper limb, ‘The sternum has been dragged outwards to the
left side, showing the under surface of its left osseous moiety and trifid
cartilages. The mammary gland and enlarged lymphatics partially occupy
the right side of the chest. On the left side of the neck the jugular veins
are intact, and the rete mirabile, cervical and axillary, superficially displayed.
On the right side a deeper view is given. ‘The large venous trunks and
portion of the rete mirabile are removed, exposing the cervical and axillary
plexus of nerves. The digastric muscle is cut away, and the parotid gland
everted.

Heart and vessels:—v, right, and v*, left ventricles; a, right, and a*, left auricle;

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 199

p.a, pulmonary artery; ao, aortic arch, and ao*, abdominal aorta; /.c, left common
carotid artery; Js, left subclavian; 7, innominata; r.c, right carotid; th, thoracic
branch ; éc, internal carotid; ec, external carotid ; im, internal maxillary and plexus ;
Jf, facial; rs, right subclavian ; ¢.ax, thyroid axis, and aa, axillary trunk splitting into
retial divisions; ).rete, brachial retial plexus; im, internal mammary; ve, portion of
vertebral artery under the pneumogastric nerve.

I.J, left internal jugular, and E.J, external jugular veins; CO, communicating branches
of the same; S.V, left subclavian vein, cut short; BC, ditto brachio-cephalic ; VCD
& VCA, vena cava ascendens and descendens, severed. ;

Nerves :—Nos. 2 to 8 numerically apply to the individual elements of the cervical and
brachial plexus; ph, phrenic; pn, pneumogastric; 77, recurrent laryngeal ; s/, superior
laryngeal; hy, hypoglossal; ¢/, inferior laryngeal; fn, facial nerve ; /t, long thoracic ;
mn, median nerve ; ec, external cutaneous; wn, ulnar nerve.

Larynx, glands, &c. :—C, cricoid, and 7, thyroid cartilage ; 0h, basihyal; sh, stylo-hyal,
and *, its cranial cartilage; tr, trachea; Pgl, parotid gland; Mg/, mammary gland;
rm, first rib; st, sternum reflected; c*, the three sternal cartilages; P, pericardium
opened; @, cesophagus, in part.

Muscles :—Wa, masseter; Stm, sterno-mastoid; Pe &c., panniculus &c. reflected; Pma
& Pini, pectoralis major and minor; Zo, external oblique, a portion; D, diaphragm ;
Cth, crico-thyroid; Th.h, thyro-hyoid; Sh, stylo-hyoid ; Sph, stylo-pharyngeus ; Ih,
mylo-hyoid.

PLATE XXV.

Illustrations of the brain of the female, partly from rough sketches when fresh, and
partly from the hardened brain, aided by a cast of the cranial cavity. All about
natural size.

Fig. 31. Upper surface.

Fig. 52. View in profile.

Fig. 33. The base, with origin of nerves.

Fig. 34. Longitudinal and vertical mesial section, or inner face.

Fig. 35. Left hemisphere, exposing lateral ventricle; the horizontal section of the
cerebellum is cut at a lower plane than is the cerebrum.

The following lettering applies throughout :—

Nerves :—1, 2, 3, 4, 5, 6, 7, 8, 8*, 9; that to the olfactory is placed on the bulb.

Parts of base :—pi, pineal gland; a, corpora albicantia; cr, crus, or peduncle; pv, pons
Varolii; ap, anterior pyramid.

Interior horizontal and vertical sections :—ac, anterior cornu; dc, descending cornu; pe,
posterior cornu; cs, corpus striatum; ts, tenia semicircularis; th, thalamus opticus ;
hmi, hippocampus minor; f, fornix; cc, corpus callosum; g, its genu, and sp, sple-

VOL. VIII.—PaRT 111. September, 1872. 26

200 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE.

nium ; @, anterior commissure; c‘, corpora quadrigemina; v*, fourth ventricle; v°,
fifth ventricle.

Lobes of cerebrum :—F, frontal; P, parietal; 7, temporal; O, occipital.

Fissures, or sulci:—sy, sy’, sy’, Sylvian; if, infero-frontal; mf, midfrontal ; sf, supero-
frontal; ap, antero-parietal; 70, Rolando, or postparietal; op, occipito-parietal ; of,
occipito-temporal ; ca, calcarine; em, calloso-marginal.

Folds or gyri:—Jo, interorbital; Jo, midorbital; Eo, entorbital; Jf, infero-frontal ;
Mf, midfrontal; Sf, supero-frontal; Ap, antero-parietal (premier pli ascendant) ;
Pp, postparietal (second pli ascendant); Lob, lobule of postparietal; Ang, angular ;
At, antero-temporal; Mt, midtemporal; P#, posttemporal; Soc, Supraoccipital ;
Moe, midoccipital; Joc, infero-occipital; U, uncinate; Ma, marginal; C;, callosal.

Cerebellum :—av, arbor vite; sv, superior vermiform process or middle lobe; 7,
flocculus ; ag, amygdaloid lobe.

Fig. 36. Portion of skull of female Manatee, with calvarium removed to show interior base.
The dura mater is in place on the left moiety, but cleared away on the right.

Lettering applicable to the left half:—1, olfactory fossa; 2, foramen piercing mem-
brane for optic nerve &c.; 3, perforation transmitting third and fourth nerves &e. ;
5 & 7, foramina respectively for trigeminal and auditory nerves &c.; ca, carotid
groove; t, temporo-sphenoidal fossa; /, pituitary fossa; j, jugular groove; pa, plexus
and lateral sinus; pa*, spinal plexus.

Lettering of right half:—/r, frontal bone; Maz, maxillary; Os, orbito-sphenoid ; As,
alisphenoid; Bs, basisphenoid; Bo, basioccipital; Ho, exoccipital; Sg.d& Pa, squamo-
parietal; P, periotic; 7, tympanic; 2*, optic groove; 7, meatus auditorius internus;
Sc’, superior semicircular canals ; c, c*, condyles.

PLATE XXVI.

Fig. 37. Longitudinal and partly median section of the body, head, &c., of the young
male Manatee, 4 nat. size. The ribs are left in position, but dissected so as
to show the remarkable relations of the lungs, diaphragm, and viscera
generally.

L, L, L, L, L*, the lung resting on D, D, D, D, D*, the lengthened horizontal dia-
phgram ; /sf, ligamentum subflavum of dorsal vertebre; f, coating fat and skin of
the back; H, heart; St, sternum; Ji, liver; Sto, stomach; J, folds of intestine ;
B, urinary bladder; P, penis within its sheath; Rab, rectus abdominis and cut
fleshy wall; B.c, bulbous cavernosus muscle; cv, ischio-cavernosus ; Sp.a, sphincter
ani; A, anus; Js.c, ischio-coccygeus; Se+Jf.c, sacro-coccygeus and infra-coccygeus,
obliquely cut through ; fc, fibrous caudal expansion with a rim of the skin left ; but
on the opposite right side the skin has not been removed; P/, pelvic bone; Pf, pelvic
suspensory fascia; C.Rete, the rete mirabile which proceeds to the end of the tail

DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 201

within the chevron bones; L.Fete, lumbar vascular rete shown in part; Be, brain-
cavity; 2.ch, nasal chamber leading by narrow canal to n, external narial orifice ;
Pmx, premaxillary bone in section, covered by the fleshy, fibrous snout; sy, mental
symphysis; w/, upper lip (=outer); up, upper pad (=inner lip); J/, lower lip
(=outer); Jp, lower pad (=inner lip); 0h, buccal hairs; 7, tongue; Evws, orifice
of Eustachian tube; Sgh, stylo-glossus and hyoid muscle; a double-headed arrow
beneath leads from the fauces to the cesophageal and laryngeal passages, each
partially laid open ; Ja, cut larynx; @, esophagus; Rete &c, portion of rete cervicale ;
J & C, jugular vein and carotid artery severed; Md: F, muscle and fat between the
fore limbs; cv, cervical vertebre.

Fig. 38. Front segment of the skull, showing the nasal cartilage on the right side, and

the open nares, diminutive nasal bone, &c. on the left.

Fr, frontal bone; Na, left nasal; Tw, turbinals; 0, right orbit; nc, nasal cartilage ;
sp, septal cartilage ; cf, cartilaginous fissure ; Px, infraorbital plexus of arteries.

Fig. 39. A transverse section of the tail behind the anal constriction, but in advance of

the caudal expansion. It shows:—c, centrum of a vertebra, its articulating
surface surmounted by the neural arch (@) enclosing the spinal cord, which
is surrounded by a vascular plexus; ¢, cut surface of transverse process,
between which and centrum is another rete mirabile; ch, lamina of chevron
bone enclosing subcaudal rete; Lci, Lce, levatores caude internus and ex-
ternus or continuation of the dorsal muscles; J.c, lumbo-caudalis; Sc¢ and
If.c, sacro-coccygeus and infra coccygeus, lower tail-muscles; Sz, skin, fatty
fibro-fatty layer, &c.

Fig. 40. A cross section of the flat expanded tail: vt, vertebra; ¢’, levator caudal tendons,

and ¢’, depressor caudal tendons surrounding the bone; f, fatty and fibrous
tissue, containing the open mouths of nourishing vessels; sk, skin, its fibroid
subdermal layer, covered by a black line representing the derm and cuticular
covering.

. A portion of the root-end of the lung, with its vessels minutely injected:

&, bronchus; 6b, bronchia; v, pulmonary vein, and a, artery; /, lobule.

. The right eyeball, mesially and vertically divided, and posteriorly other orbital

contents. Parts about natural size, and from the female Manatee.

O. Rete, orbital vessels; m, muscles; on, optic nerve; ion, infraorbital nerves; ca, ciliary
artery ; sc, sclerotic; cp, ciliary processes; /, lens.

Fig. 43. A transverse section of the same eye behind the ciliary processes and iris.
Fig. 44. A ventral view of the female body eviscerated and dissected, chiefly to show

the long tendinous diaphragm and kidney thereupon, the intercostal vascular
plexuses, and the lumbo-caudal muscles.

202 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATER.

1, 2, 3, 4, 5, 6, the cervical vertebree; cc, costal cartilages of the sternal ribs; ao, arch
of the aorta; JcRete, intercostal rete; Zi, internal intercostal muscles; D, D*, dia-
phragm of right side, in situ; K, kidney thereupon; V, renal vein; w, ureter;
Eo, posterior termination of external oblique muscle; Q/, quadratus lumborum,
internal to which portion of lumbar and caudal rete (C. rete) is seen; Sc, sacro-
coccygeus entire on right side, and cut edge on left; Jf.c, infra-coccygeus; L.cd,
partial view of lumbo-caudalis.

Fig. 45. The uterus, minus ovaries and fimbrie, seen deeply, or on its dorsal aspect.
The parietes are cut open: Ut, uterus ; os, os tine ; Ic, left cornu; R, rectum;
fete, lumbar rete; Px, uterine plexus.

Fig. 46. A continuation of fig. 45, displaying the pelvic parts from below the muscles,
the retial vessels as they spread out, and part of that which runs under the
tail.

L.Rete, lambar or hypogastric rete ; C.Rete, caudal rete; Pl, pelvic bone; fad, portions
of rectus abdominis; Isc, ischio-coceygeus; Pc, termination of panniculus carnosus ;
pn, nerve piercing the tissues close to pelvis.

Fig. 47. The glans penis in its sheath, or male parts corresponding to those of the
female shown in the succeeding figure: s, sheath slit open and dragged out ;
g, glans ; mu, meatus urinarius.

Fig. 48. A reduced sketch of the vulva, the skin and superficial tissues having been
removed: cl, clitoris; mu dv, vulva and meatus urinarius; Spv, sphincter
vaginee.

Fig. 49. Sketch of the posterior abdominal region in the male, the parietes &c. being
removed, and a deep dissection made on the left side. The penis has been
cut away near its root; and what remains, along with the bladder, are seen
turned backwards.

P, penis, and pa, its artery; B, bladder; vd, vasa deferentia; Te, testicle; H.Rete, rete
mirabile of loins and _pelvo-generative region ; 7, tips of three hindmost ribs; R,
rectum; A, kidney; g/, gland; wu, ureter; v, vein; a, artery; D, diaphragm.

Fig. 50. A dissection of the left moiety of the pelvic region of the female, exhibiting
the pelvic bone in place, its muscular attachments, the vast lumbar rete
mirabile, and relation of the uterus, kidney, and bladder to each other.

D, D*, diaphragm; K, kidney; v, renal vein; a, artery; w, ureter; B, bladder; V,
vulva; A, anus; #, rectum; Pl, pelvic bone; c¢, cornu; f, fimbria; 0, ovary; ha,
hypogastric artery; H.Rete, hypogastric or lumbar vascular plexus; Pc, Pc, panni-
culus, severed; Rab, Rab*, rectus abdominis; Eo, external oblique; L.cd, lumbo-
caudalis; Se, sacro-coccygeus; Is.c, ischio-coceygeus; Sp.a, sphincter ani; Sp.v,
sphincter vaginee; Zc, levator ani; Tp, transversus perinei; E.c, erector clitoridis.

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