INDIVIDUAL VARIATION IN EQUUS ASINUS. 723 
to that which occurs in the ox is, of course, of no morphological 
value. 
Canines long or short, sexual variation. 
Premolars: small “ wolves' teeth '' occasionally present in 
front of four anterior molars. 
Stomach often presents a very marked central transverse con¬ 
striction where cuticular mucous joins the villous. 
Caecum sometimes retains the forms it presents in eight months' 
foetus; its apex sometimes very elongated and pointed. 
Colon .—Longitudinal muscular bands vary in size and in 
number at different part of the bowel. 
Liver .—Lobes vary in form and much in size. Ligaments 
differ in degree of development, especially falciform ligament, 
which sometimes runs as far backwards as umbilicus, containing 
a pervious vein in its thin free margin. 
Parovarium .—On outer surface of broad uterine .ligament, 
sometimes large, often obsolete. 
Male mammae often extremely large. 
Thyroid body varies much in form, especially in the size of the 
band connecting its lateral masses. Conchial cartilages pro¬ 
longed downwards by small rounded band to lateral part of 
guttural pouch and to posterior angle of stylohyal. A remark¬ 
able peritoneal band sometimes runs from the ceecum to the 
omentum major, reminding us of a condition we have noted in 
one form of Macacus. 
Angiology. 
Anterior aorta often entirely absent. Sometimes a larger 
anterior mediastinal branch passes downwards from this vessel. 
The dorsal and posterior cervical vary in their relations to each 
other. Generally these vessels are united on the right side and 
distinct on the left; but this condition may be reversed. The 
cervical may become united by a well developed subcostal with 
the sixth costal as given off from the posterior aorta ; but this is 
not constant. The vetebral passes through or below the seventh 
cervical transverse process. The submaxillary may arise directly 
from the carotid instead of from the external carotid. External 
pectoral arises from internal pectoral, or axillary. 
Posterior aorta .—Bronchial and oesophageal often arise by 
common root, or are distinct. Benal may supply suprarenal 
capsules and kidney; or the former may be supplied directly by 
a branch from the posterior aorta. Spermatics—one sometimes 
considerably more anteriorly placed than the other, even given 
off by posterior mesenteric. Between internal iliacs occasionally 
a small middle sacral arises. The obturator, epigastric, and 
inguinal sometimes arise from external iliac, ine origins of the 
profunda and of the artery of the cord often vary. 
