406 
apparatus in the Mo- 
notrematous quadru- 
peds must be classed 
with the accessory or- ~ 
gans of generation in 
the same category with 
the antlers of Deer, the 
spurs of the Cock, the 
claspers of the Shark, 
and other peculiar 
characteristics of the 
male sex. It has been 
already shown, in the 
description of the 
young Ornithorhyn- 
chus, that the external 
of thea tus 
ete so aeeened 
as to distinguish the 
sex at that immature 
period ; a small spur, 
concealed in a cavity 
or socket of the inte- 
pe covering the 
eel, the bottom of 
which closely adheres 
to the accessory tarsal 
ossicle, exists in both 
sexes; a magnified 
view of the part in the 
young female is given 
at fig. 197. As the 
young animal advances 
to maturity the cutane- 
ous socket increases in 
land and spur, 
ithorhynchus. 
( Mechel. ) 
width and depth in the female, but without 
any corresponding growth of the rudimentary 
spur, of which in aged female Ornithorhynchi 
sometimes no trace remains. In the male 
Omithorhynchus the tarsal spur soon begins to 
rise above the socket, and finally attains a 
length of ten lines with a basal breadth of 
five lines, apparently everting the tegumentary 
socket in the progress of its growth. The spur 
(fog. 173, K, e; fig. 202, e) consists of a firm 
semitransparent horn-like substance: it is coni- 
cal, slightly bent, and terminated by a sharp 
point; its base is expanded, and notched at 
the margin for the implantation of the ligaments 
which connect the spur with the accessory flat 
tarsal bone (os basilare, Meckel,) (fig. 173, k, 
d; fig. 202, d.) The base of the spur is co- 
vered by a thin vascular integument. The 
spur is traversed by a canal which commences 
at the centre of the base and terminate. by 
a fine longitudinal slit, about one line distant 
from the point, closely resembling in this 
respect the canal that traverses the poison 
fang of the venomous snake.* Like that canal 
also the spur of the male Monotreme is sub- 
servient to the transmission into the wounds it 
may inflict of the secretion of a peculiar gland. 
is gland (a, Je: 202) is situated in the 
Ornithoth nchus at the back part of the thigh, 
between the femur and the long process from 
the head of the fibula, covered by the integu- 
* De Blainville in Bulletin de la Société Philo- 
mathique, 1817, 
MONOTREMATA. 
ment and the cutaneous muscle. It is of a 
triangular or reniform figure, convex above, 
concave below, or towards the leg; from twelve 
to fourteen lines in length, seven or eight lines — 
broad, and three or four lines thick, with a — 
smooth exterior, invested by a thin capsule, — 
on the removal of which the gland may easil; S 
be divided into a number of small lobes. Its — 
intimate structure, as displayed by a successfu 
injection of mercury, is minutely cellular, like” 
that of the glandula Harderi of the hare or 
goose, but with the ultimate secerning cells” 
more minute; the excretory duct is conaaiay 
from the concave side of the gland, and — fs 
clusters of vesicles are developed from parts” 
of its expanded commencement.* The duct, 
(fig. 180, 1,) which is about a line in width 
sak with pretty strong tunics, descends pres) 
down the back of the leg, covered by the 
flexor muscles and posterior tibial nerve, to 
the posterior part of the tarsus, where it sud- 
denly expands into a vesicle (b, fig. b 
about three lines in diameter ; vesicle is — 
applied to the base of the spur, and a minute — 
duct (c, fig. 202) is continued from it into the 
canal which traverses the spur. 
The tarsal perforated spur and its j 
apparatus are both relatively smaller in the 
male Echidna than in the i = 
The gland is situated lower down, in the 
popliteal region, between the insertions of the — 
deep-seated fasciculi of the adductor femoris” 
and the origins of the gastrocnemius; it is of 
subspherical form, about the size of a pea, — 
with a smooth exterior; the excretory duct, 
wide at the commencement, soon contracts into 
a filamentary canal, which again enlarges to — 
form a small reservoir for the secretion just 
above the base of the spur. fe 
The true nature and use of this apparatus 
has not yet been determined. Its close ry 
with the poison apparatus in other ani 
obviously suggests the idea of a corresponding 
function, but no well. authenticated case of — 
symptoms of poisoning consequent upon a — 
wound inflicted by the spur has been d.: 3 
It seems on the contrary that the Ornithorhyn- 
chus possesses not the instinct of availing itself 
of a weapon so formidable, as upon this thee 
the spur must be, when attacked or ann: 
Mr. George Bennett tried the following experi- 
ment with a full grown wounded but lively 
male Ornithorhynchus :—“ I commenced by — 
placing my hands in such a manner, when 
seizing the animal, as to enable it, from th 
direction of its spurs, to use them with 
the result was that the animal made strer ; 
efforts to escape, and in these efforts scratched” 
my hands a little with the hind claws, and 
even, in consequence of the position in which 
I held it, with the spur also. But althoug 
seized so roughly, it neither darted the 
into my hand nor did it even make an att 
so to do. As, however, it had been sta 
that the creature throws itself on the back wh 
it uses this weapon, (a circumstance not very 
ecoraed. 
oat 
* Miller, De Glandularum 
it. Struct. Pp. 3, 
tab. ii. fig. 10. ee pl 
