MARSUPIALIA. 



The tubuli testis are relatively smaller than 

 in the Rodentia, but are similarly arranged, the 

 corpus Highmorianum being near the surface 

 and upper part, not at the centre, of the gland. 

 The epididymis is large, and generally loosely 

 attached to the teslis : in a small species of 

 Kangaroo I found the connecting fold of serous 

 membrane half an inch broad. The vasa de- 

 ferentia pass from the globus minor along the 

 infundibular muscular sheath formed by the 

 cremaster as far as the abdominal ring, then 

 bend downwards and backwards, and termi- 

 nate below and external to the ureters, at the 

 commencement of the urethra (a, fg. 135), 

 on each side a longitudinal verumontanal ridge. 

 There are no vesiculae seminales in any Mar- 

 supial quadruped. 



Fig. 135. 



A , Hypslprymnus. B, rhascolarctus. C, Phascolomys. 



As the part of the urethral canal immediately 

 succeeding the termination of the vasa defe- 

 rentia is the analogue of the vagina, some mo- 

 dification of this part might be anticipated in 

 the male corresponding with the extraordinary 

 form and developement which characterise the 

 vagina in the female : accordingly we find that 

 the combined prostatic and membranous or 

 muscular tract of the urethra is proportionally 

 longer and wider in the Marsupial than in any 

 other Mammiferous quadrupeds (Jig- 135, 6). 

 It swells out immediately beyond the neck of 

 the bladder, and then gradually tapers to its 

 junction with the spongy part of the urethra : 

 it is not, however, divided like the vagina. 

 Its walls are thick, formed of an external thin 

 stratum of nearly transverse muscular fibres ; 

 and a thick glandular layer, the secretion of 

 which exudes by innumerable pores upon the 

 lining membrane of this part of the urethra. 

 In a male Kangaroo I found that a glairy mucus 

 followed compression of this musculo-prostatic 

 tract of the urethra: the canal itself is here 

 slightly dilated. 



Three pairs of Cowper's glands (c, c, c, fg. 

 135) pour their secretion into the bulbous 

 part of the urethra : the upper or proximal 

 pair are not half the size of the two other pairs 

 in the Kangaroo, but are relatively larger in 

 the Koala and other Marsupials : the two 

 lower pairs are situated, one on each side the 

 lateral division of the bulb of the urethra ; 

 their ducts meet and join, above this part, with 

 the duct of the smaller gland : each gland is 

 inclosed by a muscular capsule. 



The penis consists of a cavernous and a 

 spongy portion, each of which commences by two 

 distinct bodies. The separate origin of each late- 

 ral half of the spongy body constitutes a double 

 bulb of the urethra ( e, e. Jig. 1 35), and the ' ac- 

 celerator urina?,' as it is termed, undergoes a 

 similar division into two separate muscles, each 

 of which is appropriated to compress its par- 

 ticular bulb. The two bulbous processes of 

 the corpus spongiosum soon unite to surround 

 the urethra, but again bifurcate to form a dou- 

 ble glans penis in the multiparous Marsupials, 

 in which most of the ova are impregnated in 

 both ovaria, as the Phalangers, Perameles, 

 Opossums, &c. (b,b,fg.l36). 



This modification of the opposite extre- 

 mities of the corpus spongiosum, called ' bulb ' 

 and 'glans,' was detected by Cowper in his 

 dissection of a male Opossum ; and, in his 

 account of the anatomy of that animal in 

 the Philosophical Transactions for the year 

 1704, he says, " As the bulb of the urethra 

 in man is framed for the use of the glans, to 

 keep it sufficiently distended when required, 

 so it seems it is necessary to have (wo of 

 these bulbs, inclosed with their particular mus- 

 cles in this animal, to maintain the turgescence 

 of its double or forked glans when the penis is 

 erected." Vol. xxiv. p. 1585. 



The force of this ingenious, reasoning on the 

 correlation of the bulb to the glans might seem 

 to be invalidated by the fact that in the uniparous 

 Marsupials, as the Kangaroo, the glans penis 

 (f,fg. 135) is single, and yet the bulb double : 



