74: Corpora Cavernosa in the Domestic Cat 
and 3). This bone is by no means constant in its occurrence. Of the 
specimens examined, in 7 kittens (2 half-grown), and 5 small-sized cats, 
no trace of an os penis was found. In 9 specimens of medium-sized 
cats, 3 showed a very small rudimentary os penis, the others none. Of 
12 large-sized cats, 8 had a well-developed os penis (3 mm. to 5 mm. 
long); 2 a small or rudimentary bone; and 2 no trace of bone. It there- 
fore appears that the os penis of the male cat is inconstant and acquired 
relatively late in life, certainly not until long after sexual maturity. 
The os penis, when well developed, is about 5 mm. long and shaped 
like a long tapering cone. It is placed dorsal to the urethra, and the 
apex extends beyond the meatus externus to near 
the tip of the glans. The bone is slightly flattened 
from side to side (Fig. 3). The base of the os penis 
lies embedded in the septum between the distal ends 
of the corpora cavernosa, in the base of the glans. 
At this extremity, the bone is flattened dorso-ven- 
trally, and presents dorsally on each side, a groove in 
which rests the end of the corresponding corpus 
cavernosum. 
The os penis is usually a solid bone, but occasion- 
ally contains a medullary cavity. Around the bone 
and forming a conical projection beyond its tip is a 
strong fibrous periosteal layer, which is a prolonga- 
tion from the tunica albuginea, and especially from 
the septum. A similar prolongation exists as a dense 
fibrous cylinder in cases where the bone is unde- 
veloped, even distinctly in the penis of the new-born 
cat. The os penis therefore may be considered as 
tre Gormestie coms of the ossified distal prolongation of the septum be- 
PEE ae aa tween the corpora cavernosa. It is not preformed 
ate in cartilage, thus differmg from that of the dog, as 
described by Retterer.’ 
The corpora cavernosa throughout the greater part of their extent 
are closely united to each other in the median line, the septum being 
very slight or incomplete (Fig. 5). Distally, however, they become 
slender and diverge to end in the base of the glans, on each side of the 
os penis. The structure varies greatly in the different regions. To- 
ward the distal extremity, the corpora cavernosa are composed almost 
entirely of compact adipose tissue, supported by slight fibrous trabeculae 
2 Retterer, E., Sur Vorigine et l’evolution variable de la charpente qui existe dans 
le gland des mammiferes. C. R. Soc. de Biologie, Paris, 1886. 
