MALE ORGANS OF MAKSUP1ALS. 647 



gland is enclosed 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 lateral half of 

 the spongy body constitutes a double bulb of the urethra, ib. e, e, 

 and the i accelerator urinas,' as it is termed, undergoes a similar 

 division into two separate muscles, each of which is appropriated 

 to compress its particular bulb. The two bulbous processes of 

 the corpus spongiosum soon unite to surround the urethra, but 

 again bifurcate to form a double glans penis in the multiparous 

 Marsupials, in which most of the ova are impregnated in both 

 ovaria, as e.g. in the Phalangers, Perameles, Opossums, &c, b, b, 

 fig. 504. In the uniparous Marsupials, as the Kangaroo, the 

 glans jienis, fig. 503, f, is single. 



The intermediate structures of the glans between the two ex- 

 tremes above instanced are presented by the Ursine Dasyure, 

 Koala, and Wombat. In the Koala, fig. 503, b, the glans penis 

 terminates in two semicircular lobes, and the urethra is continued 

 by a bifurcated groove along the mesial surface of each lobe. In 

 the Wombat, ib. c, there is a similar expansion of the urethra 

 into two divergent terminal grooves, but the glans is larger, 

 cylindrical, and partially divided into four lobes : the chief pecu- 

 liarity in this part of the Wombat is the callous external membrane 

 of the glans, and its armature of small recurved, scattered horny 

 spines. The small retroverted papillae on the infundibuliform 

 glans of the Koala and on the bifurcate glans of the Phalangers and 

 Petaurists are not horny. In the Perameles lagotis not only is the 

 glans bifurcate, but each division is perforated, and the urethral 

 canal is divided by a vertical septum for about half an inch before 

 it reaches the forked glans : from the septum to the bladder the 

 canal is simple, as in other Marsupials. The divisions of the glans 

 in the Opossums, fig. 504, b, and Phalangers are simply grooved. 



The corpus cavernosum penis commences by two crura, figs. 

 503, 504, d, d, neither of which have any immediate attachment 

 to the pelvis. In the Kangaroo these crura, and the two bulbs of 

 the corpus spongiosum, soon unite to form a single cylindrical 

 body, the blended cavernous and spongy structures forming the 

 parietes of a canal which nearly follows the direction of the axis 

 of the penis, and contains or constitutes the urethra : a transverse 

 section of the corpus cavernoso-spongiosum thus resembles a ring; 

 but the lateral erectile tracts are separated by two vertical septa 

 which extend from the central canal, the one to the dorsum penis, 

 the other to the inferior wall : in this case there is no definite 

 commencement of the glans penis ; its termination is that of the 



