262 



MARSUPIALIA. 



As the she one has a false belly, for the conveyance of her young, it 

 may be reasonably supposed that she does not make any sort of nest for 

 the young, but that she carries them from place to place. 



In its genitals the opossum partakes both of the quadruped and bird ; 

 for its testes are in the usual place, but the penis is within a small 

 orifice just at the termination of the anus ; and, when it is pulled out, 

 it inverts a little part of the anus : the rectum is turned down, as it 

 were, from the tail to join the penis. What the position of the penis 

 is when erected I cannot say ; but it seems to be backwards, or at least 

 at right angles with the body. If so, they must copulate tail to tail, 

 and the situation of the penis with respect to the testicles or scrotum 

 would make this very probable ; for, let us suppose that the penis is 

 turned forwards in the time of erection, it must come directly against 

 the testicles, for the scrotum will be directly against the mouth of the 

 vagina 1 ; or it may be supposed that they copulate similar to a bird, or 

 probably like the rat or rabbit, which are somewhat different from the 

 common quadruped ; although in these two animals the testicles are not 

 so pendulous, and are by the sides of the penis. 



The penis is forked at the end, and the urethra opens at the union of 

 the two forks, and a groove is continued from the urethra along each 

 fork, like the groove in birds. The testicles are very pendulous, the 

 scrotum hanging by a small neck : it is white, while the skin of the 

 attachment, or neck, is grey : but this varies in different opossums. 

 The tunica vaginalis testis does not communicate with the abdomen, 

 being in that respect as in man. The tunica vaginalis is of a dark grey 

 colour (in one at least). The epididymis is attached to the testicle by 

 a broad and very thin transparent membrane ; as also is the vas deferens 

 to the epididymis. If it was injected with quicksilver, the ducts coming 

 from the testicle would be very plain to be seen. There are no vesiculae 

 seminales. The ureters open very near the opening of the urethra, and 

 are therefore very near to each other : the urinary bladder opens into 

 the urethra, which is of a singular construction. That part which is 

 between the bladder and scrotum, which is called ' membranous ' part, 

 is about 4 inches long : it seems to be twisted ; it is thick in its cavity, 

 but particularly so near the bladder. It would seem to be made up of 

 two kinds of substances ; for, on looking on it, one is dark, the other is 

 light brown ; yet both are glandular. The dark substance is divided by 

 the light brown into portions ; one at the opening into the bladder, 



1 [In the coitus of the kangaroo, which was ' more canino,' I noticed that the 

 scrotum was obliterated by the retraction of the testes, which appeared to be forcibly 

 compressed against the marsupial bones of the male. — Philosophical Transactions. 

 1834, p. 334.] 



