522 MR, F, E. BEDDARD ON THE [Apr. 27, 
Hochstetter *, where a prevailing left posterior vena cava was 
accompanied by aright spermatic vein opening into the right 
renal vein and a left spermatic opening into the postcava itself. 
This is the exact reverse of the normal conditions obtaining in 
Man, where, as in so many animals, it is the left genital vein 
which pours its blood into the left renal while the right-hand 
vein enters the postcava directly. 
T have only examined one example of the American Monkey 
Ohrysothri sciureus, and it is rather remarkable to find that that 
one specimen, not in any way selected, should show a variation ; 
for so I must in the present state of our knowledge interpret the 
conditions shown by the postrenal section of the postcaval vein. 
The vein was in fact, as in Chiromys just dealt with, developed 
on the left side instead of the right. It lay very distinctly to the 
left of the aorta. Corresponding with this abnormality in the 
position of the postcaval, its principal branches showed an entirely 
similar position to those of Chiromys and the human abnormality 
which I have compared with it. For of the two ovarian veins 
the left entered the main trunk of the postcaval some little way 
down the latter, while the right ovarian vein poured its contents 
in the posteaval just below the entrance of the right renal vein. 
T cannot but think that in the normal arrangement of the veins 
of this animal the postcaval was on the right side of the aorta 
and the position of the two ovarian veins was reversed, the left 
being anterior to the right. 
S$ Résumé and General Considerations. 
It is, in the first place, clear from what has been detailed in the 
foregoing pages, and from my previous papers in which the post- 
caval system is dealt with, that the postcaval system of veins in 
Mammals is subject to variations of an individual character. 
This conclusion is not of course deduced from my own work only, 
but from what has been written by others which I am able to 
confirm for other animals and from additional examples of species 
already known. Even in the very few individuals of certain 
species which I have been able to dissect, variation has always been 
noticeable. Forinstance, in three specimens of Chiromys varia- 
tions occur; in four examples of J/ctonyx capensis, in three of 
Hystrix cristata, in two specimens of Hrinaceus ewropeus, in two 
of Suricata tetradactyla, in three examples of Dasywrus maculatus. 
And these variations together nearly cover the range of variation 
which the posteaval and its branches show among the Mammalia. 
In spite, however, of these variations from individual to indi- 
vidual of a given species, there are certain characteristics of 
groups which may be laid down with some confidence, and with 
more confidence—I venture to assert—from a consideration of 
the new facts which I bring forward here. 
* Loc. cit. p. 638. This paper contains a good many references to the literature 
of venous abnormalities in man, as well as descriptions of instances. 
