188 MR. W. A. FORBES ON THE KOALA. [Jan. 18, 



in one of my specimens, three columna carnecB, which also decrease 

 in size from right to left. On the side corresponding with the 

 septum the valve is attached, not to a columna carnea, but by 

 chordce tendinecB inserted on the septal wall. There is apparently 

 only a single opening for the coronary veins, just at the entrance of 

 the inferior cava into the auricle. 



The aorta gives oflF, in the specimen which died in the Society's 

 Gardens, three vessels from a common trunk, and then the left 

 subclavian, as in Phalangista and most other Marsupials'. In 

 another specimen, however, the arrangement is as in Man and as in 

 Phascolomi/s, the left carotid arising independently from the aortic arch. 

 Of the two vencB azygos, each opening into the superior cava of its side, 

 the left is much the larger, the right being formed mainly by vessels 

 derived from only the first few intercostal spaces, whilst below these the 

 veins of the right side pass over, behind the aorta, into the lefL azygos. 

 This is an arrangement I have found in several Marsupials examined, 

 including Phascolomys, Belideus, Cuscus, and Phalangista, though 

 not in Petrogale or Hypsiprymmis. In Phascolomys there exists a 

 commissural branch between the first intercostal vein on the right 

 side going to the left, and the last going to the right, vena azygos. 

 In the Hedgehog, and some other animals according to Prof. 

 Owen (Auat. Vert. iii. p. .553), the right is also smaller than the 

 left azygos, though usually the reverse condition holds ; and in the 

 highest forms, where there is only one vena azygos, it is the right 

 that persists. 



The external and internal iliac arteries come off separately from ■ 

 the aorta, there being no common iliac arteries. This disposition is, I 

 believe, nearly universal" in the Marsupials, but is by no means confined 

 to them, as I have found it in Tamandua, Tapirus, and Hyomoschus, 

 and Prof. Watson records it in Hycena crocuta (P. Z. S. 1879, p. 89). 



The lungs are simple in form. The right side has three, the left 

 two lobes ; the lower lobes of each side being about equal in size, 

 and much larger than the others — half as big again as the upper, 

 or two upper, lobes. There is no azygos lobe at all. 



The female generative organs of Phascolarctos have not been, so 

 far as I have been able to ascertain, hitherto described, though Mr. 

 A. H. Young has lately given us an excellent account, with figures, 

 of the corresponding system in the male. In their essential points 

 they differ in no important respect from those of the Wombat ^ 



' P.S. Feb. 11, 1881. In a fresh specimen of Belideus hrcviceps, which I 

 have just dissected, I find only one tnmk ai'ising froui the aortic arch ; this 

 splits up into 3 branches — a left innominate, dividing into tlie subdavian and 

 carotid branches for that side, a right carotid, and a right subclayian. More- 

 over, as in no other Marsupial known to me, there is only one anterior civa, 

 the right and left innominate veins joining to form a larger trunk, some ^ inch 

 long, whicli opens into the auricle. 



- In a Cuscus mactdatus that I dissected I found the abdominal aorta splitting 

 up into four trunks, the right and left external, and the right internal iliacs, 

 whilst from the remaining or median (caudal) one, the left internal iliac was 

 given off some way below the level of the other. 



^ For description of these see Owen, P. Z. S. 1836, p. .52, and Auat. Vert. iii. 

 p. 680 et seq. 



