DE. J. MUKIE ON THE ANATOMY OF THE SEA-LION. 571 



cular fibres covering the whole length of its exterior. This is the true compressor 

 urethrae ; and, as far as my dissection enables me to judge, the muscular sheet in question 

 comprehends what, in human anatomy, have been respectively termed the circular fibres 

 of Santorini, or stratum internum circulare of J. Miiller, the constrictor urethra', and the 

 levator prostata?. The compressor urethrae, then, in Otaria jubata embraces the membra- 

 nous portion of the urethra in such a way that it appears to surround the parts spirally. 

 The fibres posteriorly are partially continuous with those of what has been named by 

 some anatomists the " sphincter vesica 1 " They are very sparse over the prostate, how- 

 ever, and, on reaching the membranous portion of the urethra, apparently divide into 

 two thick symmetrical halves, which have a direction downwards and forwards towards 

 the anus and pubes. These fleshy moieties may be taken as the equivalent of Guthrie's 

 muscle in the human being, which would seem to be but the continuation forwards of 

 the outer oblique fibres of the bladder, Pettigrew's figure-of-8 loops. In front and 

 below, a laterally compressed band of fibres goes towards, and joins, through the recto- 

 vesical fascia, the levator ani muscle. This portion seems to represent the "levator 

 prostata?" of Santorirri, Albinus, and Soemmering, and to be the fibres known as Wilson's 

 muscle. Some few fibres, again, extend upwards to the symphysis pubis; these are 

 analogous to the constrictor urethrae of some human anatomists, and may be what has 

 been described as the ascending portion and origin of Wilson's muscle. 



The bulbo-cavernosus muscle is made up of strong fibres, which curve round the bulb 

 as in other Camivora &c. The erectors of the penis have origin from the ischial 

 tuberosities ; and each, as a thick carneous mass curvilinear in figure, is inserted into the 

 side and postero-inferior surface of the enlarged crus penis. 



The sphincter ani internus is strong and broad. It powerfully constricts the lower 

 part of the rectum and anus for an inch or more. The circular fibres join those of the 

 transversus perinaei, levator ani, and retractores penis. There is also an external sphincter 

 of the anus, which is of considerable size. 



Reference and figures of the unusually large and peculiarly inserted levator ani and 

 transversus perinaei muscles are given in Part II. ; so that nothing further need be said 

 of them in this place. 



c. J Genital Glands, Scrotum, &c. — Prostate gland. — Surrounding the urethra for 

 an inch in antero-posterior extent, and of a cylindroid or spindle-shape, is the very 

 moderately raised glandular body of the prostate. Its structure is compact and finely 

 textural, merging almost indefinitely in the fibres of the sphincter vesicae behind, and 

 equally continuous with the urethral walls in front. The efferent canal and ejaculatory 

 ducts appear to open at the minute orifice of the sinus pocularis an inch in advance of 

 the apertures of the ureters. 



There are no vesiculae seminales ; and bodies representing Cowper's glands are absent, 

 or so small as to escape observation. 



Testes and surrounding parts. — Enveloped in a strong, but loose, tunica vaginalis, the 



