SYMPATHETIC NERVES OF HYRAX CAPENSIS. 153 



the lesser curvature, and the latter supplies the fundus. Both 

 groups anastomose with branches from the right vagus, and with 

 the cceliac plexus. The cord formed by the right vagus and part 

 of the left one supplies the dorsal aspect of the stomach almost to 

 the pylorus. Its branches anastomose with those of the left 

 vagus, and twigs from the coeliac plexus. A well-marked branch 

 (splanchnic ?) runs to the left sympathetic cord (A). Many of 

 the oesophageal nerves run postei'iorly and anastomose with both 

 vagi, so there is a close network round the lower end of the 

 oesophagus and over the left part of the stomach. 



The Sympathetic Nerves. 



The Superior Cervical Ganglion (text-fig. 6, s.c.g) is round or 

 oval, and flat. It gives ofi' an internal carotid nerve of con- 

 siderable length (i.c.n) which accompanies the internal carotid 

 artery into the skull. The nerve communicates with the glosso- 

 pharyngeal and hypoglossal nerves, and the ganglion is connected 

 to the vagus, cervical plexus, and loop between the superior and 

 recurrent laryngeal nerves. But no connection exists between 

 either and the spinal accessory nerve. From the posterior pole 

 of the ganglion the sympathetic cord runs laterally and joins the 

 vagus at the level of the middle of the th^^-oid cartilage to form 

 the vago-sympathetic cord. 



In Hyrax, as in all animals possessing the vago-sympathetic 

 cord, no middle cervical ganglion is present, and no direct rami 

 communicantes run to the middle cervical nerves. 



The sympa,thetic separates again in the posterior part of the 

 neck, but communicates with the vagus after the partition. It 

 exhibits a well-marked inferior cervical ganglion (I.C.G) on the 

 left side, but none on the right. From the ganglion branches of 

 communication run to the brachial plexus, but I was unable to 

 detect any communication between the right sympathetic and 

 brachial nerves, or between either cord and phrenic nerves. The 

 right sympathetic gives off a branch which accompanies the 

 vertebral artery (V.A.N), and a loop connects it to the right 

 recurrent nerve. And as no branch runs directly to the cardiac 

 plexus, the right recurrent and right vagus nerves conduct all 

 the right sympathetic filaments to the heart. 



The left inferior cervical ganglion gives off a medium-sized 

 cardiac branch (c.B.s) which runs almost parallel to the left 

 recurrent nerve, passes to the dorsal aspect of the aortic arch and 

 ends in the deep cardiac plexus. 



The Avmdus of Vieussens (A.Y) is present only on the left 

 side, and the right sympathetic cord passes in front of the right 

 subclavian artery. 



The left sympatJietic thoracic cord (text-fig. 8, L.s) has few 

 ganglia in its anterior part, and it forms loops. At the level of 

 the middle of the root of the left lung it divides into lateral and 

 mesial divisions. The former possesses a loop and a small ganglion, 



