ON THE ANATOMY OF THE KOALA. 181 



not to a columna carnea, but by cJiordce tendinece inserted on the septa 1 

 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 off, in the specimen which died in the Society's 

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

 as in Phalanyista and most other Marsupials *. In another specimen, 

 however, the arrangement is as in Man and as in Phascolomys, the left 

 carotid arising independently from the aortic arch. Of the two vence 

 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 leftazygos. This is an arrange- 

 ment I have found in several Marsupials examined, including Phascolomys, 

 Belideus, Cuscm, and Phalangista, though notiu Petrogale orHypsiprymnus. 

 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 (Anat. 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 110 common iliac arteries. This disposition is, I believe, 

 nearly universal t 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 Hyaena 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 



* P.S. Feb. 11, 1881. In a fresh specimen of Belideus breviceps, which I have just 

 dissected, I find only one trunk arising from the aortic arch ; this splits up iuto 3 

 branches a left innominate, dividing into the subclavian and carotid branches for 

 that side, a right carotid, and a right subclavian. Moreover, as in no other Marsupial 

 known to me, there is only one anterior cava, the right and left innominate veins 

 joining to form a large trunk, some % inch long, which opens into the auricle. 



t In a Cuscus maculatus 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. 



