REPORT ON THE MARSUPIALIA. 165 



Prostatic portion of the urethra (fig. 7). — For about an inch and a half from its 

 commencement, the urethra is widely dilated and fusiform in outline. From this 

 onwards it presents a uniform calibre. The vasa deferentia, which pierce the urethral 

 wall very obliquely, open upon the floor of this portion of the canal by two slit-like 

 openings (fig. 7, b) placed close together, and about a quarter of an inch from the neck 

 of the bladder. Up to this point the mucous lining of the tube is perfectly smooth, but 

 immediately beyond, it is raised into a series of delicate and faintly marked longitudinal 

 ridges which extend along the whole length of this part of the urethra. In the intervals 

 between these ridges the prostatic ducts open in rows. These are quite visible to the 

 naked eye, and on subjecting the prostate to pressure a small quantity of a brownish viscid 

 fluid is observed to ooze out through the minute orifices. 



There is not the slightest trace of a veru-montunal eminence in the Thylacine ; nor 

 is there any indication of a sinus pocularis. 



Cowpers glands (fig. 6, h and h 2 ). These are four in number, two being placed upon 

 either side of the mesial plane, the one in front of the other. The anterior gland on each 

 side is about the size of a pigeon's egg, and it has a reniform shape ; the posterior gland 

 is about half the size of the other and overlaps it slightly. A long slender duct emerges 

 from the centre of each and the four ducts thus derived all enter the urethra at the point 

 where it sinks into the erectile tissue of the corpus spongiosum. But further, each of 

 these glandular bodies is enveloped by a complete and thick capsule of muscular fibres 

 which is continued for a short distance upon the duct. Small fleshy slips connect these 

 capsules with the levator penis muscle of the same side. 



Penis (fig. 6). — The body of the penis measured, from the junction of the crura 

 to the extremity of the glans, six inches. It consists of the usual constituents, viz., 

 two corpora cavernosa, and a corpus spongiosum. At the extremity of the organ the 

 corpus spongiosum is split into two so as to form a forked glans penis. 



Posteriorly the corpora cavernosa separate widely from each other to form the crura 

 (fig. 6,f. and f.g-). Each crus ends in a blunt rounded point, and is enveloped in a 

 thick layer of muscular fibres. In length it is about two inches, and is firmly fixed to 

 the margin of the pubic arch in its middle third. The posterior end is therefore free, 

 and surrounded as it is by a muscular capsule it appears at first sight to belong to the 

 Cowperian glands with which it lies in series. 



The bulb of the penis, as is usual in Marsupials, is split mesially into two equal 

 portions (fig. 6, i). These are rounded in form and are about the size of an ordinary 

 marble. Each half is continuous by means of a broad pedicle with the erectile tissue of 

 the corpus spongiosum of the body of the penis and each is covered by a thick capsule 

 of muscular fibres which apparently take origin from the aponeurosis investing the 

 pedicle. 



Muscles of the Penis. — The penis is supplied with four pairs of muscles, viz. : — 



