REPORT ON THE SPHENISCID^. 145 



anterior portion of the oesopliagus. This branch evidently represents the " arteria 

 oesophagea descendens " of Barkow. 



(b) The Palatine Artery arises from the external carotid above the origin of the 

 lingual artery, and passes forwards to gain the roof of the mouth. Here it lies between 

 the pterygoid muscle and the papillated mucous membrane of the palate, and after 

 extending forwards parallel to the palatal fissure, terminates close to the anterior 

 extremity of the bony palate, by inosculating with its fellow of the opposite side. A 

 number of small branches are supplied by the palatine artery to the anterior portion of 

 the oesophagus, as well as to the soft parts in the neighbourhood of the palate. 



As the palatine artery passes forwards it gives off a branch of considerable size, which 

 winds upwards round the inner border of the pterygoid muscle, to gain the upper or 

 orbital surface of that structure, where it develops a coarse arterial rete, which occupies the 

 floor of the orbit. This rete, moreover, receives a communicating branch from the trunk 

 of the internal carotid artery after that vessel has passed into the interior of the skull. 

 From the plexus of blood-vessels so formed, numerous branches are given off. A few of 

 these branches supply the pterygoid muscle, but much the greater number pass forwards, 

 and terminate by supplying the structures occupying the anterior inferior angle of the 

 orbit, and the basal region of the superior maxillary bone. 



(c) The Anastomotic Artery. — The artery which I have thus named comes off from 

 the external carotid artery, and passes obliquely backwards and outwards to gain the deeper 

 surface of the panniculus carnosus muscle. Here it gives off numerous branches to the 

 superior and lateral surfaces of the neck, and terminates by inosculating with the 

 subcutaneous cervical artery. It thereby completes an important anastomosis between 

 the commencement of the common and that of the external carotid arteries. This artery, 

 like the subcutaneous cervical, lies alongside of the vagus nerve and jugular vein. 



In Pygosceles tceniatus the anastomotic artery is given off from the internal carotid, 

 \t\x of an inch from the origin of the latter. 



(B) The Internal Carotid Artery. 



After separating from the external carotid, the internal cartoid artery passes inwards 

 to reach the base of the skull, where it traverses the carotid canal, and thereby reaches 

 the interior of the cranium. Here it divides into two terminal branches, an anterior and 

 a posterior. The anterior extends alongside of the sella turcica, and divides into two 

 branches, of which one passes vertically upwards to supply the cerebral hemisphere, while 

 the other (the ethmoidal) leaves the front of the cranial cavity by means of a special 

 foramen, and reaching the orbit, terminates by breaking up into branches for the supply 

 of the straight muscles of the eyebaU. The posterior terminal branch of the internal 

 carotid passes backwards and supplies the cerebellum. 



From the internal carotid artery, in addition to the terminal branches just described, 



(ZOOL. CHALL. EXP. PART XVIII. — 1883.) S 19 



