1894.] ON THE VISCERAL ANATOMY OE ORNITnORHYNCHTTS. 715 



There is no separate inferior mesenteric artery, in this respect 

 agreeing with certain Marsupials. 



Arteries of Head and Neck. 



The common carotid. — Is a large artery arising from arch of 

 aorta on left side, from innominate on the right. It divides at 

 about the level of the thyroid cartilage into external and internal 

 carotid. Just at the point of bifurcation an artery is given off 

 which passes directly inwards and divides in a regular cross-like 

 manner into ascending, transverse, and descending. The ascending 

 and descending pass to the pre-vertebral muscles ; the transverse 

 to the back of the larynx and trachea. 



The external carotid. — Passes upwards and backwards ; gives 

 off a branch to the supra-hyoid and genio-hyoid muscles. More 

 anteriorly a small lingual artery arises. There is a second smaller 

 lingual just above this, next to submental branch which runs 

 along the whole length of the inferior surface of the lower jaw, 

 close to the bone. Coming off here, in addition, are two slender 

 branches, one passing to the sub-lingual gland, the other to super- 

 ficial structure, skin, &c. A little higher arises an artery which 

 divides almost immediately into two branches, one passing to the 

 inner surface of the lower jaw, the other to the outer surface ; they 

 may represent internal and external pterygoid arteries. The 

 internal is fairly large and gives off several branches to the cheek- 

 pouch. The trunk artery passing a little further on divides into 

 two branches ; one, passing to the superficial structures on the side 

 and roof of the skull, is distributed to the deep structures in these 

 regions. 



Internal carotid. — Passes deeply at the neck and divides into 

 two branches. The smaller passes deeply beneath pharynx and in 

 front of the longus colli muscle to the anterior margin of foramen 

 magnum. The other is the continuation of the trunk, passes 

 upwards and enters the skull. 



2. On some Points in the Visceral Anatomy of Ornitho- 

 rhynchus. By Frank E. Beddard,, M.A., F.R.S., Pro- 

 sector to the Society. 



[Eeceived December 4, 1894.] 



Mr. B. P. Lascelles, assistant master at Harrow School, was 

 so good as to allow me to examine a frozen Omithorhynchus which 

 he had obtained for the purpose of making a skeleton for the 

 Butler Museum at Harrow. After thawing, I found the viscera 

 in a very fair condition for anatomical investigation, though they 

 were naturally somewhat softened. 



The first point to which I directed my attention was the 



