102 THE AMERICAN NATURALIST. [VoL. XXXIV. 
The middle sacral vein and the * Connecting branch” (V. 2/- 
aca communis sinistra) must be developed in close relation with 
each other, since the former normally opens into the latter. It 
is not. strange, therefore, in one 
instance (Fig. 3) where the 
‘“« Connecting branch ” is abnor- 
mal, that it should arise from 
the middle sacral vein. 
2. ON THE PRESENCE OF UN- 
USUALLY Lonc Common ILIAC 
Dextra Sinistra 
- 
= 
= 
= 
p 
Fic. 6. Fic. 7. 
Fic. 6. Pru NOTE Miseum, Ao bo. Unusually long Vv. iliacæ communes 
vhich unit vertebra. Ventra l aspect. 
iliaca communis. . mesenterica post. For remaining numbers, se e Fi 1g. I. 
Fic, 7. peri Morphological can No. 6o Same as Fig. 6. Ventral aspect. M 
teries omitted in the drawing. WR A Misi X. Opposi igin of Aa. iliace externe 
from aorta. For remaining indien. see Fig 
Veins (Vv. iliace communes). — The point at which the single 
postcava joins the right and left common iliac veins is normally, 
with slight variations, opposite the middle of the seventh lum- 
bar vertebra. In three cats, not including those which pos- 
sessed well-defined double postcaval veins, the point of union 
of the two common iliacs with the common postcava was 
found to be opposite the middle of the sixth lumbar vertebra, 
* 
