REPORT ON THE SPHENISCID^. 143 



parallel with, and close to the posterior border of the ulna. It terminates by anastomosing 

 with the next branch. 



(d) A branch coming off from the ulnar artery, just before the latter leaves the palmar 

 surface of the wing, passes obliquely downwards and inwards below the wrist joint, and 

 reaching the posterior border of the wing extends as far as the tip of that organ. By 

 means of the anastomosis of this with the preceding branch, there is formed a vessel which 

 extends along the whole length of the posterior margin of the wing from the elbow joint to 

 the tip. This vessel lies alongside of the brachial vein. 



(2.) Tlie Common Carotid Artery. 



In all the Pengfiiins vi'hich I have examined, there are two common carotid arteries of 

 equal size, both of which occupy the inferior middle line of the neck. Each after separ- 

 ating from the trunk of the innominate artery is directed forwards and inwards, and 

 gains the middle line of the neck at a point which corresponds to the great inferior 

 convexity of that portion of the vertebral column. Here the arteries of opposite sides 

 come into contact. Thereafter they pass directly forwards, lying in the interval between 

 the longi colli muscles of opposite sides, the artery of the left lying slightly below (in 

 front of) that of the right side. The arteries lie in contact as far as the middle in 

 length of the groove between the recti antici majores muscles, but beyond this point 

 diverge from one another, and after cror>sing the front of the corresponding rectus anticus 

 muscle, each divides opposite the posterior extremity of the mandible into the carotis 

 cerebralis and the carotis facialis. The two common carotid arteries are of equal size, 

 and have similar relations except at their terminations. The artery of the right side, in 

 consequence of the deviation of the trachea and oesophagus from the middle line crosses 

 these tubes, while the left carotid artery has no relation to them. 



In Aptenodytes, on account of the lesser deviation of the oesophagus and trachea from 

 the middle line of the neck in that genus than in Eudyptes, both the common carotid 

 arteries at their termination come into relation with these tubes. 



The common carotid artery, in addition to the external and internal carotids, gives 

 off four named branches, all of which arise from the parent trunk one inch from its 

 commencement. They are the oesophageal, the transversalis colli, the vertebral, and the 

 arteria cutanea colli. 



The (Esophageal Artery. — This is a small branch which comes off from the common 

 carotid close to the thyroid gland. It passes obliquely forwards and inwards, and 

 coming into contact with the oesophagus, supplies the walls of that tube. 



The Transverse Cervical Artery is likewise a small branch, which, after leaving the 

 common carotid, passes transversely outwards, and supplies the soft parts in the neigh- 

 bourhood of the shoulder joint and on the dorsal surface of the scapula. 



The Vertebral Artery. — After leaving the carotid trunk this branch is directed 



