TRANSVERSE DEVELOPMENT OF THE FOETUS OF THE MARE. 303 
transverse development of the body of the uterus, practically 
prohibits any linear uterine development or extension so that 
the actual forward displacement must take place at the ex¬ 
pense of the vagina. But by what means does the foetus at¬ 
tain a position posteriorly to the os uteri and beneath the 
floor of vagina? 
The most tenable theory to me is, that in the earlier stages 
of this transverse development, the foetus lies with its back 
downwards towards the inferior abdominal walls, and the 
abdomen upwards toward the spine of the mare, which is the 
normal position of the foetus at this stage when normally sit¬ 
uated in one of the cornua. 
With the foetus developing in the body of uterus, the two 
cornua, not bearing their normal weight, would naturally as¬ 
sume a practically perpendicular position. When, however, 
the hind and fore extremities attain considerable size and 
weight and push their way up into the cornua, the equilibrium 
of the foetus is soon disturbed and the newly attained weight 
bears the cornua downwards, increasing the tension upon the 
vagina and the superior walls of the uterus, the body of the 
foetus partially turning on its axis, decreasing the tension on 
the interior uterine wall, and by this turning, displacing and 
pushing it upwards and backwards, against the inferior vagi¬ 
nal wall, the back of the foetus resting against the pubis of 
the mare. 
The diagnosis of this anomaly should prove comparatively 
easy. We note the abnormally long and narrow vagina ; the 
absence of the usual projection of the os uteri into the vagina, 
and in its stead an abrupt opening of variable size, downwards 
and backwards at the extreme anterior end of the vagina ; the 
foetus lying more or less transversely, inferiorly to the vagina 
and posteriorly to the os, where it can readily be felt through 
the vaginal and uterine walls, and generally, the inability on 
the part of the mare to make any true expulsive effort. 
The prognosis must be uniformly grave, some cases offer¬ 
ing apparently insurmountable obstacles to delivery, while in 
those cases, where after herculean labor, the obstetrist suc¬ 
ceeds in removing the foetus, he finds that a fatal rupture has 
