702 ox THE AYE- AYE AND OTHER LEMURS. [Juiie 16, 



of the left side poured its contents into the ovarian vein at its 

 origin. I did not succeed in tracing the corresponding vein of 

 the right side all the way; but in any case it commenced 

 anteriorly in exactly the same way as the other vein. It will be 

 noted, therefore, that the conditions obtaining in Chiromys could 

 be arrived at by an obliteration of the connection of the ovarian 

 vein of the left side with the postcaval, and the retention only of 

 its embouchure into the renal. 



I may observe that in an example of Galago gariietti the origin 

 of the ovarian veins was quite as in Chiromys. On the other 

 hand, in a male of Nycticehits tcuxligradus, the arrangement was 

 slightly different from, though not in great disagreement with, 

 Chiromys and Galago. In Nycticebus in fact the left spermatic vein 

 poured its contents into the left renaL The right, on the other 

 hand, opened into the postcaval, though very near to the point of 

 origin of the here more or less symmetrically arising renal veins. 



The internal mammary veins of Chiromys run one on each side 

 and in association with the artery at some distance from the 

 middle line of the sternum. The two veins are connected with 

 each branch of the single precaval vein where it bifurcates at the 

 front end of the thoracic cavity. This is quite the normal 

 arrangement for these veins, but I mention the facts since there 

 are sometimes differences. For example, in Lutra vtdgaris I 

 found the internal mammary a single vein on the right side, 

 but with several branches supplying the left side of the middle 

 ventral line. Moreover, it is also desirable to note that each of 

 these veins runs closely accompanied by its artery strictly parallel 

 to the middle line of the sternum but at some distance from it. 



The azygos vein is not figured by previous investigators of the 

 anatomy of Chiromys. I have examined this vein (text-fig. 152) in 

 each of the three specimens which I dissected, and most carefully 

 in the last example which was a young female. It is developed only 

 upon the right side of the body, as in all Lemurs hitherto studied. 

 It is a well developed vein and extends backward to nearly the 

 diaphragm. The first branch supplies two intercostal spaces, and 

 the last branch of the series but two is also divided in the same 

 way. There was no trace that I could discover of any corre- 

 sponding vein upon the left side, neither was there a hemiazygos. 

 The point at which the intercostal arteries pass outside of the 

 azygos vein is a matter which varies much among mammals. 

 But the material does not as yet exist for a use of the facts for 

 systematic purposes. It is, however, obviously permissible to 

 state the conditions observed in Chiromys with a view to future 

 generalisations. I found, in fact, that in this Lemur the first of 

 the series of intercostal arteries to cross over the azygos vein, 

 as viewed in the ordinary position of dissection, was that lying 

 behind the tenth rib. Thereafter all the intercostal arteries 

 had the same position. In front of this point they underlay 

 the vein. 



