IN THE ORNITHORYNCHUS PARADOXUS. 152 
the contained fluid passed out perpendicularly upwards, and 
not in the direction of the vas deferens itself : a small mu- 
cous papilla is placed near the orifice of each vas deferens *. 
But previous to our proceeding farther with the description 
of these organs, we must revert to the more external parts, 
and describe the cloaca itself. 
It is well known that, externally, one orifice only is seen 
in the male ornithorynchus, which is to serve for the pas- 
sage of the solid and liquid excrement, and of the penis. 
This orifice, situated at about 4| inches from the extremity 
of the tail, opens into a considerable cavity, generally called 
the cloaca f. When this cavity is slit open very carefully, 
we perceive three orifices of different dimensions, the uses 
of which are easily discovered. The highest up, which is 
also the largest, is the extremity of the rectum J ; the se- 
cond, at about i*gths of an inch from the former, is the 
opening of the urinary urethra; and the third, situated 
close to the former, passes into a sheath, in which the penis 
is entirely concealed. On the surface of the cloaca, near 
the termination of the rectum, are five or six small dark- 
coloured orifices, by which a few very small glands pour 
their secretions into the cloaca. If the urethra be now laid 
open from behind, that is, on the side which regards the 
• The description taken at the time of the dissection, is as follows :— 
These ducts open close to the entrance of the urethra into the bladder, by 
a narrow linear aperture, the lower edge of which forms a sort of valve." 
•f It is to be regretted that this name of Cloaca was adopted, taken as it 
is from the class of birds. The same structure exists in the beaver; and 
hence we see evidently the impropriety of the name " Monotr ernes given 
by some French naturalists to the Echidna and Ornithorynchus ; under which 
appellation, they ought also to include the Castor tribe. 
X The length of the cloaca, from its external orifice to the opening of 
the rectum, is about 1 jo^h inches. 
