218 AIonoteemata. MAMMALIA. Oknithokhynchidas. 
examination, several oviparine features will be imme- 
diately discovered. M. Geoffrey St. Hilaire first gave 
the name of Monotremata to the small group of non- 
placental marsupial mammals here associated together, 
tliereby indicating the termination of the urino-genital 
and intestinal passages by a single cloacal outlet — an 
arrangement also found in birds and reptiles. Equally 
striking peculiarities affect the skeleton, these being 
more especially manifest in the presence of two clavicles 
nearly conjoined, and applied against the upper surface 
of a single furcular bone ; there are also well-developed 
coracoid bones, which are articulated to the sternum. 
In addition to this there are special osseous elements, 
termed epicoracoids, which are connected to the sternal 
and furcular bones, the scapulae being likewise attached 
to the breastbone. In the accompanying woodcut 
(fig. 93), the furcular bone or episternum presents a 
Fig. 93. 
Stern.al apparatus of the Duck-bill (Ornithorhynchus paradoxusj. 
T-shaped outline, with the lateral free ends directed 
towards the shoulder-blades. It conceals the clavicles, 
which are slender bones and not united at the mesial 
line. The epicoracoids are seen interposed on either 
side of the stem of the furcular bone, resting laterally 
on the thick coracoids, which latter are articulated to 
the episternum and manubrial bone of the sternum 
below and to the scapular above. Another circum- 
stance worthy of remark is that the bones of the skull 
become very early consolidated ; those of the face 
being much prolonged forwards and flattened out into 
the form of a beak, which is covered by a smooth, 
naked integument. The jaws are not furnished with 
teeth ; but their place is supplied by numerous rows of 
horny dentelations, having their spinous points directed 
towards the throat, as obtains in the analogous buc- 
cal papillae in the mouths of ruminants. They also 
exist on the tongue in the form of conical papillae. 
The feet are short, particularly strong, and pentadac- 
tylous. The Monotremes have small eyes, no external 
ears, and very short tails. In the male Duck-bill the 
hind feet are armed with a perforated spur, its channel 
containing an excretory duct belonging to a special 
glandular structure placed at the back part of the 
thigh. This remarkable organ was formerly supposed 
to be a poison gland ; but there is no good ground for 
such an opinion. Neither is it merely a weapon of 
offence and defence ; for then we should probably not 
have the gland in connection 'ufith the spur, and the 
females would probably also be similarly armed. We 
have no doubt in our own mind that it is analogous to 
those supernumerary organs often found in the males 
of the lower as well as in the higher animals. “ Since 
then,” says Professor Owen, “ this apparatus forms a 
sexual character, it may be presumed that its function 
is connected with that of generation. Whether the 
spur be a weapon for combat among the males, or — ■ 
like the spiculum amoris of the snail — be used to 
excite the female, the injected secretion being an addi- 
tional stimulus ; or -whether the spur be mechanically 
useful in retaining the female during the coitus, are 
conjectures which must be verified or disproved by 
actual observation.” The females are furnished with 
mammary glands ; but there are no external teats. 
The manner in which the function of lactation is per- 
formed, and many other facts bearing upon the question 
as to how the offspring are reared, still remain to be 
explained. 
Family I.— ORNITHOEHYNCHID^. 
This family is represented by a single species, which 
is readily distinguished from the members of the suc- 
ceeding family by its non-fossorial, palmate feet. It is 
also furnished with eight horny, tooth-like formations 
regularly disposed, two on either side above and below. 
The crowns of the anterior pairs are long and thin, 
those of the posterior set being broader and oval. The 
snout is prolonged, compressed, broad, and covered 
by a naked coriaceous integument; the lower jaw is 
shorter and narrower than the upper, and marked 
posteriorly by transverse lines. The tongue is very 
peculiar; the anterior half or narrow portion being 
covered with coarse papiUm, whilst the posterior division 
is broad, slightly overlapping the former, and armed 
hi front by two prominent horny spines. The ornitho- 
rhynchus is furnished with cheek-pouches. The I'ur is 
hairy throughout ; the tail being flattened, broad, and 
conspicuous. 
THE DUCK-BILL {Onnihorhynchun paradoxus), or 
Australian Water Mole — Plate 31, fig. 99 — is a 
native of New South Wales and Van Diemen’s Land. 
A full-grown individual varies in length from eighteen 
to twenty inches, including the tail, which measures 
about five inches. The fur exhibits a tawny or rufous 
colour, one or other of these tints prevailing in different 
varieties. In the young state the skin is entirely 
destitute of hair, and the jaws are short, soft, and 
flexible. In the adult the tongue is placed far back, 
the tip being fully an inch behind the anterior opening 
of the bill. According to Professor Owen, “ the 
raised posterior lobe of the tongue must impede the 
passage of unmasticated food to the pharynx, and 
doubtless tends to direct it on each side mto the cheek- 
pouches, whence the ornithorliynchus may transfer its 
store at leisure to the molar teeth, and complete its 
prefiaratiori for deglutition. An air-breatliing, v/arm- 
blooded animal, which obtains its food by the capture 
of small aquatic animals while submerged, must derive 
great advantage from the structure wdiich enables it to 
transfer them quickly to a temporary receptacle, whence 
they may be extracted and masticated while the animal 
is floating on the surface or at rest in its burroiv.” 
