Page 789, 
228 THE VISCERAL ANATOMY OF THE GROUND-RAT. 
The specimen being a male, those generative organs only can be 
described. The ureters enter the bladder at about one third its length 
from the neck. The vesicule seminales are two inches long, being 
composed of tubes with irregularly situated lateral diverticula of small 
size; they enter the urethra: separate from the vasa deferentia, which 
are not swollen at their urethral ends. The testes are abdominal, 
being situated at the entrance of the capacious abdominal rings, with 
strong muscular gubernacula attached to the bottom of the would-be 
scrotum. The epididymis of each testis is of about one fourth its size. 
The prostate is, like that in most Rodents, composed of closely related 
but not intercommunicating bundles of glandular substance, arranged 
in elongated conical bundles, which can be easily separated from each 
other, each being about two thirds of an inch long. The membranous 
urethra is 3 inches long; Cowper’s glands are about the size of peas, 
dark red and subspherical. The os penis is half-an inch long; and 
its free end forms part of a lip-like projection over the top of the 
orifice of the urethra. 
There is a gland, the shape of the hearts on playing cards, fixed 
at its apex, which opens into the anterior wall of the termination of 
the rectum, just within the sphincter ani; it is white in colour, and 
the size of a haricot bean. 
The most striking peculiarity in the above described anatomy of — 
this animal is in the arrangement of the cecum, which differs from 
that of most of the Cavies I have had the opportunity of examining in 
not presenting an abrupt change in the character and direction of the 
gut at the point of junction of the cecum and colon. Respecting its 
osteology it may be mentioned that there are thirteen ribs, and that 
the clavicle was not developed from end to end in this not fully adult 
specimen, the sternal extremities being cartilaginous and joined to the 
free termination of a broad cartilaginous spatulate manubrium sterni. 
In a skeleton in the British Museum the broad bifurcate acromion is 
not preserved on either scapula; and they do not seem to have been 
broken off. In the specimen above described, this big acromion is 
present on both sides, but, peculiar to relate, it is in each only joined 
to the main part of the spine of the scapula by a fibro-cartilaginous 
ligament, and no crepitus is felt on moving the one part on the other. 
Tf this condition is not the result of injury, which it does not seem to 
be, it is very abnormal. 
The peculiarities of the skull make me inclined to place Aulacodus 
nearest to Lagostomus and the American Porcupines, the former of 
which it very closely resembles in the arrangement of the zygomatic 
arch and palate, though the teeth present considerable difference. 
The cecum of Lagostomus appears to be in many respects similar ; 
but the liver is less complicated, possessing no cystic notch or fossa. 
