of the Ornithorhynchus paradoxus. 81 
within the anus there is a valvular projection, between the rec- 
tum and vagina, which appears to be the proper termination of 
the rectum. This also is similar to the bird. 
There was no appearance of clitoris, that could be observed. 
The vagina is inch long : its internal membrane is rugous ; 
the rugae being in a longitudinal direction. At the end of the 
vagina, instead of an os tincae, as in other quadrupeds, is the 
meatus urinarius ; on each side of which is an opening leading 
into a cavity, resembling the horn of the uterus in the quadru- 
ped, only thinner in its coats. Each of these cavities terminates 
in a fallopian tube, which opens into the capsule of an ovarium. 
The ovaria are very small : they were hot in a very perfect 
state of preservation, but bore a general resemblance to those 
of other quadrupeds. 
This structure of the female organs is unlike any thing 
hitherto met with in quadrupeds ; since, in all of them that I 
have examined, there is the body of the uterus, from which the 
horns go off, as appendages. The opossum differs from all 
other animals in the structure of these parts, but has a perfectly 
formed uterus ; nor can I suppose it wanting in any of the class 
Mammalia. 
This animal having no nipples, and no regularly formed 
uterus, led me to examine the female organs in birds, to see if 
there was any analogy between the oviducts in any of that class, 
and the two membranous uteri of this animal ; but none could be 
observed ; nor would it be easy to explain how an egg could lie 
in the vagina, to receive its shell, as the urine from the bladder 
must pass directly over it. Finding they had no resemblance to 
the oviducts in birds, I was led to compare them with the uteri of 
those lizards which form an egg, that is afterwards deposited in 
mdcccii. M 
