VOL. XXIV.J PHILOSOPHICAL TRANSACTIONS. 115 



part in men. These vesiculae are not only compressed by the thin broad 

 sphincter muscle above mentioned, but the bulbs of the cavernous bodies of the 

 penis cc, and urethra ee, when distended in the erection of the penis, also 

 compress these mucous bags. This compression in men is effected by the in- 

 tumescence of the bulb of the cavernous body of the urethra, Phil. Trans. 

 N° 258. In boars, rams, cats, &c. nature is so solicitous to discharge the con- 

 tents of the excretory ducts of these glands, that, like the gizzard of birds, each 

 mucous gland is inclosed with a proper muscle to compress it. 



The penis fell next under my examination, the fabric of which appears not 

 less surprising, than what is met with in the uterus of the female ; and in many 

 circumstances differed from what I have found in all the animals that I have 

 hitherto dissected: besides the forked glans of its penis, bb, its cavernous bodies 

 DD, fig. 2, 3 had no connection with the ossa pubis, nor did the muscles called 

 erectores, or directores, cc, adhere to any bone, as in men and quadrupeds 

 but all those parts lay loose under the ossa pubis. The other extremities of the 

 two corpora cavernosa penis are received into the glans. Nor did the corpus 

 cavernosum urethras e, or its muscles ee, fig. 3, adhere to the sphincter ani, 

 as in most other animals, but the whole body of the penis lay loose between the 

 bones of the pubis and the rectum ; so that on the intumescence or erection of 

 the penis, it i^ at liberty to be extruded from its praeputium, wherein it is 

 secured from outward injuries when not erected. To favour this extrusion of 

 the penis in this animal, the urethra ikl, fig. 2, is not only very long between 

 it and the bladder oo, but is much more contorted or folded in acuter angles, 

 than is expressed in the figures, otherwise the penis could not be extruded, but 

 the bladder oo must follow it. Besides, it appears that nature designed this 

 extrusion of the penis of this animal in its erection, because we meet with in- 

 struments to draw it back again into the praeputium. ffG show a pair of 

 muscles, elegantly framed for that purpose, on the forepart of the penis ; they 

 arise fleshy from the corpora cavernosa penis dd, and becoming tendinous ff, as 

 they pass through two ligaments or pulleys on the ossa pubis, and are afterwards 

 united into one tendon g, which is inserted at the upper part or dorsum penis. 

 Besides this pair of muscles, which is peculiar perhaps to this animal, I found 

 another pair of muscles hh, fig. 2, 3, that also withdraw the penis, arising from 

 the rectum, and are inserted into the extremities of the corpora cavernosa penis : 

 in cats, male porpoises, bulls, rams, and boars, we meet with two ligaments 

 springing from the os sacrum or ilium on each side, and inserted into the corpora 

 cavernosa penis of those animals, which like these muscles serve to draw in the 

 penis of those animals into the praeputium. 



The corpora cavernosa penis of the opossum differ in their figure, from what 



a2 



