430 DR. J. MURIE ON THE ANATOMY OF THE WALRUS. 
(um), and its posterior border at 19 inches distance from the anus. Of elongate oval 
contour, 24 inches in antero-posterior, and 1 inch in transverse diameter, its puckered 
edges are capable of great distention. Radiate, semicircular, and anteriorly longitudinal 
grooves and ridges start from and surround the raised lips of the orifice. 
Two long and strong fleshy bands, the retractores penis (fig. 17, R.p), pass from the 
neighbourhood forwards to the foreskin in front, and at the sides of the os penis. 
Only a small portion of the bone (os, fig. 17) is shown; but it appears similar to that 
figured of the adult by De Blainyville in his ‘ Ostéographie,’ Atlas, tome 2, pl. vil. 
A powerful glistening aponeurosis or flattened tendinous ligament (fig. 17,7) lies on 
the dorsal surface of the bone; it arises from its proximal, and is inserted into its 
distal end; expanding forwards it is connected partly with the subcutaneous tissues of 
the prepuce, and mingles with the terminal fibres of the retractors of the penis. The 
glans anteriorly, as in Otaria, is truncate, and in the fore-shortened view (fig. 16, g) 
presents an oval contour, 14 inch in vertical and 1 inch in horizontal diameter, at the 
lower extremity of which a nipple-like pendulous portion of the corpus spongiosum 
projects. The meatus urinarius (figs. 16 & 17,mz) opens at the tip of this. The os 
penis (0s*) comes forwards to the very front of the glans, is abruptly truncate as in 
Otaria, and likewise is covered by a layer of mucous membrane, superficially roughened 
and pitted. This portion of it is almond-shaped, narrow end down, partially sur- 
rounded, excepting below, by a deep sulcus (s), which itself is outwardly bounded by 
the tumid fleshy and rugose glans (vy). The glans penis (fig. 17, ¢) altogether is about 
1} inch long, and somewhat laterally compressed; its cuticular covering bears fine 
transverse wrinkling; this is continued into the longish preputial fold (p) coextensive 
with the sheath already spoken of. 
The corpus spongiosum (fig. 17, es) is small in calibre, and only slightly visible in the 
side view and behind. The urethral bulb (0) is of fair size in this respect, contrasting 
with the moderate dimensions of the somewhat laterally compressed cylinder of the 
corpus cayernosum (figs. 17 & 18, cc), which latter is longitudinally curtailed by the 
presence of the bone, 
Immediately behind the bulb the penis lessens in girth, but again widens at its 
prostatic portion. Cowper's glands are absent; and the small prostate (fig. 18, Pr.), 
very slightly protuberant outwardly, is imbedded within the urethral walls, close to the 
neck of the bladder. 
The vasa deferentia, on entering the pelvic cavity, proceed to and separately pierce the 
prostatic portion of the urethra; and as there are no vesicule seminales, they terminate 
in two minute orifices or ejaculatory ducts (¢.d) in an elongated mesial ridge, represen- 
tative of the sinus pocularis, which runs forward in front of the prostate gland. 
In this case the manner in which the obliterated urachus entered the urinary bladder 
is worthy of mention; to wit, it formed within the viscus. 
The ureters (w, figs. 17 & 18, Pl. LIV.) open by small semilunar slits about 1 inch 
