REPORT ON THE MARSUPIALIA. 107 



Prostate (fig. 8, k). — The prostate gland presents the same shape as in Tliylacine. 

 In length it measures fully one inch, whilst its diameter at its broadest part or base 

 is about a quarter of an inch. Its anterior end or base embraces the neck of the bladder 

 whilst its narrow posterior end is gradually lost upon the urethra. 



Prostatic portion of the. urethra (fig. 10, c). — The prostatic; urethra is wide at its 

 commencement, but gradually diminishes in calibre as it is traced through the gland. 

 Its mucous lining is smooth throughout its whole length. It shows only a very slight 

 indication of the ridges which are so very evident in the Thylacine, and the orifices of 

 prostatic ducts are barely visible to the naked eye. The vasa deferentia open by two 

 minute apertures immediately beyond the neck of the bladder and there is no trace of a 

 veru-montanal eminence, or of a sinus pocularis. 



The sinus pocularis is absent in the great majority of marsupials. The disappearance 

 of all structures pointing back to the embryonic condition may be considered one of the 

 distinguishing features of the order. It is therefore a fact of the greatest interest to find 

 " an ill-defined utriculus or sinus pocularis " in the Koala. 1 



Cowpers glands (PL X. fig. 8, g, and fig. 9, b). — These are two in number. They 

 are placed in the interval between the two divergent crura — one upon either side of the 

 membranous portion of the urethra. In size they are not larger than peas, and each is 

 provided with a distinct muscular capsule and has a narrow duct proceeding from it. 

 This duct after a course of about a quarter of an inch pierces the urethral wall and opens 

 into the commencement of the spongy portion of the urethra. 



In the Vulpine phalanger the corresponding glands are four in number as in 

 Tliylacine, but they are exceedingly minute. 



Penis. — The length of the penis from the junction of the different parts of the root to 

 the extremity of the forked glans was 1^ inches. The body of the organ is composed of 

 the usual three constituents. The glans is long and forked and measured almost half an 

 inch in length ; the root of the penis has no direct attachment to the outlet of the pelvis. 

 The crura penis (fig. 8,f, and fig. 9, c) are remarkably long, having a length almost 

 equal to that of the body of the penis. They are bulbous at their extremities, and widely 

 divergent. The bulbous free end is clothed by a thick muscular capsule — the erector 

 penis — but this is at no point attached to the pelvic bone. The narrower posterior 

 portion of the crus is naked. 



The bulb (fig. 8, h, and fig. 9, d) is double. Each half lies upon the upper surface of 

 the uncovered portion of the corresponding crus, and is enveloped in a thick fleshy 

 capsule — the bulbo-cavernosus. The two portions of the bulb unite to form the corpus 

 spongiosum into which the membranous portion of the uretha sinks. 



Muscles of the penis. — These are the same as in Tliylacinus. The retractores penis 



1 Young, Jour. Anut. and Phys., vol. xiii. p. 309. 



