OF THE ORNITHORHYNCHUS PARADOXUS. 
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orifices : the largest is in the middle and conducts into the urinary bladder ; 
about three lines below this orifice are those of the uteri, situated, each on a 
small nipple-like prominence, or os tincse ; and just below these, but on the 
same prominence, are the terminations of the ureters. These prominences 
were most marked in the specimens with the largest ovary and uteri, and the 
one on the left side projects further than that on the right. 
The uteri are two distinct tubes, not arising, like the horns of the uterus in 
ordinary quadrupeds, from a cavity peculiar to them, or corpus uteri ; but 
continued, as in tortoises, from a cavity into which the urinary bladder and 
ureters separately enter. Neither is this the sole resemblance they bear to the 
oviducts of reptiles ; for, compared with ordinary quadrupeds, the distinction 
between the true uterus and Fallopian tube is but slightly marked, and the 
entire canal is thrown into many convolutions, partly by the process of peri- 
toneum, or ligamentum latum, which attaches them to the pelvic region, and 
partly by means of a ligamentous chord upon which the convolutions are, as 
it were, strung. In their natural state the uteri measure about three inches 
in length ; but when the convolutions are unfolded they extend to more 
than double that length ; the right uterus, however, being always the shortest. 
The ligament above mentioned arises from the posterior parietes of the abdo- 
men in the situation analogous to that of the testes in the male, viz. below, 
and a little to the outer side of the kidneys, and passes along the edge of the 
broad ligament to the Fallopian extremity of the uterine tube, where it divides; 
one portion is continued along the posterior margin of the orifice of the uterine 
tube, the other along the corresponding edge of the ovary; and after a course 
of an inch they again unite, and the ligament is continued along the anterior 
part of the uterus to the neck of the tube, where it is insensibly lost. The two 
separated portions of the ligament support a large pouch of peritoneum, which 
forms the ovarian capsule ; the wide anterior orifice of the uterus is also by 
means of this ligament prevented from being displaced or drawn away from 
the ovary, during the actions of the rest of the tube. 
The structure of the uterine tube is the same on both sides of the body. It 
is enveloped in a loose external serous coat, connected to the muscular coat by 
filamentary processes of cellular membrane, among which, numerous tortuous 
vessels ramify. The second tunic is a thin compact membrane, which I con- 
clude to be muscular from analogy only, having been unable, even with a 
3 y 2 
