1896. | ANATOMY OF PETROGALE XANTHOPUS. 705 
The Vhyroid body consists of two separate oval lobes about 
2 inch long, lying one on each side of the trachea without any 
isthmus connecting them. 
The Arch of the Aorta has only two branches, the innominate 
and the left subclavian; the former gives off the right subclavian, 
soon after which it divides into right and left carotids. 
The Subclavian arteries pursue a normal course and give off 
vertebral, internal mammary, and transverse cervical branches, but 
no interior thyroid or superior intercostal were seen. The common 
Carotid gives off the superior thyroid and, at the anterior margin 
of the larynx, divides into external and internal carotids, the 
former giving off lingual, facial, and occipital branches, and 
ending almost entirely in the internal maxillary, the temporal 
being very small. The superior laryngeal branch comes off from 
the lingual. 
The Avillary artery gives off weil-marked thoracic, subscapular, 
and circumflex branches. The Brachial gives off a small superior 
profunda which accompanies the musculo-spiral nerve, as well as 
a large nutrient branch to the humerus. About the middle of the 
arm, at the place where the median nerve is finally formed, a 
superficial branch comes off, which possibly represents the inferior 
profunda though it does not accompany the ulnar nerve. The 
brachial artery then passes through the supra-condylar foramen, 
after which it gives off some muscular branches and soon divides 
into posterior interosseous and median. 
The posterior Interosseous passes to the back of the forearm 
between the two bones, giving off a large posterior interosseous 
recurrent branch; while the median accompanies its nerve into the 
palm of the band, where it divides into four digital branches for 
the clefts between the digits. There is no radial or ulnar artery 
and no deep palmar arch. Owen" describes the artery which I 
have called median as the ulnar, and says that there is.also a 
radial artery. 
The Thoracic aorta shows nothing worthy of special notice. 
The Abdominal aorta gives off the celiac, mesenteric, and two renal 
arteries close together, just behind the opening in the diaphragm. 
Of the two renals the right is a little in front of the left. There is 
no posterior mesenteric artery, a condition which Owen has noticed 
in all Marsupials. The aorta trifurcates opposite the disc between 
the fifth and sixth lumbar vertebre into the caudal and two 
external iliacs. The internal iliacs are given off from the caudal 
opposite the posterior part of the sixth lumbar vertebra, as has 
been pointed out by Owen. 
The External Iliac gives off a large ilio-lumbar branch, and, just 
before reaching the brim of the pelvis, a common trunk, which 
divides into obturator and deep epigastric. 
The Common Femoral soon after its commencement gives off an 
external circumflex branch, which runs outward between the super- 
1 + Anatomy of Vertebrates,’ vol. iii. p. 541. 
