76 



DR. C. F. SONXTAG ON THE VAGUS AND 



it is, in my opinion, represented by the swelling on the vagus in 

 Canis thous (text-fig. 5), In Civettictis civetta (text-fig. 7 B) 

 it is fused with the medial border of the left vagus, but it is 

 absent on the right side. It may communicate with the right 

 recurrent nerve. Branches run to the brachial plexus, and vaso- 

 motor filaments accompany the vessels to the fore-limbs. 



In Canis thous (text-fig. 5, s.v.h.) the latter arise independently 

 from the vagus enlargement. Branches accompany the vertebral 

 artery through the cervical vertebrae. 



Cardiac branches reach the cardiac plexuses in three ways. In 

 most species they are contained within branches of the vagus. 



Text-figure 10. 



Thoracic parts of the vagus nerves in : A. Ailuriis fulgens ; B. Cynictis peni- 

 cillata ; V.P : nerve plexus round branches of the aortic arch. Other 

 letters as in text-fig. 4. 



In some forms they reach the cardiac plexuses through the plexus 

 round the aortic arch and its branches. In others they run 

 directly to the cardiac plexuses. 



The inferior cervical ganglion is united to the first thoracic 

 ganglion by one or more nerves, or by an annulus of Vieussens. 



Pulmonary bi-anches may be included within the vagus, or fine 

 filaments may run to tlie lungs from the upper thoracic ganglia. 

 It may, however, be difficult to trace the latter. 



Cardiac Plexus : — The cardiac plexus lies between the aortic 

 arch and trachea, and in some species there is an aggregation 

 of nerves with or without ganglia, lying in the position of the 



