OF THE SOUTHERN APTERYX. 281 
angles of the fold are continued into the margins of the penis, which projects from be- 
low the external orifice of the urethro-sexual cavity into the vestibular or outer com- 
partment of the cloaca. ‘The penis rapidly diminishes to a point, and its extremity is 
spirally retracted ; when stretched out, the whole length of the intromittent organ is 
1 inch and a half in length ; but this, doubtless, falls short of the dimensions of the penis 
in the recent and erect condition. An urethral groove traverses the upper, or what, if 
the penis were drawn out of the cloaca and bent forwards along the abdomen, would be 
its under surface, by an urethral or rather seminal groove, which is continued to the end 
of its spiral extremity : the margins of this groove are not beset with papille, but simply 
wrinkled transversely, as in the Emeu and Ostrich. The two lateral cavernous crura of 
the penis are attached to the membranous parietes of the uro-genital cavity, and to a re- 
tractor or erector muscle which comes off from the inner surface of the lower edge of the 
ischium: one of these muscles is represented at Pl. XLVIII. n, Fig. 3. ‘The base of 
the penis is drawn towards the coccyz, and the veins quitting the corpora cavernosa are 
compressed by a second pair of muscles (0), narrower but thicker than the erectors, 
which arise from the fascia at the sides of the coccyx, pass downwards along the sides 
of the vestibule, and meet at a tendinous raphé on the dorsum penis. Immediately above 
the base of the penis, on each side, there is a considerable plexus (p) of both arteries 
and veins, with which also many filaments of nerves are intermingled. The last- 
described muscles cross over the base of this plewus in their course to the penis, and 
would doubtless impede, if not arrest the current of blood in the veins ; they might be 
termed, therefore, “‘ compressores venarum penis,’ as they fulfil the same office as the 
compressores described by Douglas in the Dog. In this office of maintaining the erect 
and turgid state of the intromittent organ, the compressores are aided by two broad 
sphincters: the internal one (Pl. XLVIII. gq, fig. 3.) rises from the sides of the coccyx, 
and more immediately surrounds the cloaca, meeting its fellow at the middle line of the 
inferior surface : the external sphincter (r) closes principally the external compartment 
of the cloaca. 
The female organs in the specimen dissected presented their full functional develop- 
ment. The left ovarium was, however, too much decomposed to admit of any accurate 
observation of its structure being made: it consisted of an irregular and obscurely di- 
vided mass, of about three inches in length by two in thickness: the largest yelks ap- 
peared to have been about one inch in diameter. There was a perfectly distinct right 
ovarium situated in front of the corresponding supra-renal gland ; it consisted of an ir- 
regularly oval flattened body, with a slightly granulate surface, nine lines long, six lines 
wide, and about one line in thickness. The part of the cloaca where a rudimental right 
oviduct, supposing one to have been present, might have terminated, was cut away. 
The left oviduct was of large size, and from the condition of the lining membrane of 
the calcifying segment or uterus, seemed to have been exercising its function a brief pe- 
riod before death. The whole length of the oviduct was thirteen inches ; it was disposed 
VOL. II.—PART IV. 2P 
