328 Dr Duckworth, A critical description of three cases 
Such conditions of the lower limb and of the genitalia and 
intestine are strongly reminiscent of the sireniform type of monster, 
of which variety specimen E is evidently an “ incomplete ” or 
aberrant example. 
The mode of origin of the single umbilical artery (Fig. 5) is 
shewn in the accompanying plan (Fig. 6) of the branches of the 
Fig. 5. Transverse section ( x 8) through the umbilical cord of specimen E. 
The single umbilical artery is seen on the right side of the drawing. 
abdominal aorta. The latter, after giving off the coeliac axis, the 
superior mesenteric and the uppermost lumbar arteries, divides 
unequally, and the larger branch forming the main continuation 
of the parent aorta becomes the single umbilical artery of the 
cord. The point of bifurcation is too near the diaphragm to be 
regarded as the normal iliac division. Moreover, the smaller 
branch at the bifurcation continuing down the vertebral column, 
gives off smaller branches both right and left, so that it is clearly 
a much-diminished dorsal aorta. Nevertheless, on arriving at the 
pelvic brim this median dorsal aorta bears to the right, and the 
next twigs given off correspond to the internal iliac tributaries 
of the (single) inferior vena cava. Next, this artery passes into 
the thigh, and evidently becomes the common femoral with super- 
ficial and deep branches. The superficial division passing down 
Hunter’s canal is easily exposed in the popliteal space (owing to 
the outward rotation of the thigh) and becomes the popliteal 
artery as in normal examples. In this smaller branch we recognise 
thus a reduced dorsal aorta passing successively into right 
common iliac, right external iliac, right common femoral and 
other normal limb branches. The internal iliac artery is much 
diminished in size and importance, and no hypogastric branch 
could be seen. 
Returning to the larger branch into which the abdominal 
aorta divides, it is to be noted that though it passes almost 
unchanged in calibre to the umbilical cord, yet it provides an 
artery for the left sex-gland, and gives off a slender branch which 
at the pelvic margin becomes the left common femoral with such 
subsidiary branches as can be recognised in the peg-top-shaped 
left lower limb. 
