532 



MR. C. H. WABE ON THE 



the transverse trunk the passage of the blood into the right jugular 

 is effected." Van der Hoeven does not, in his ' Handbook of Zoo- 

 logy,' enter on the question at all ; nor is it referred to in the other 

 frequently used books, such as Eymer Jones's 'Animal King- 

 dom ' &c. 



Such meagre references were nofc sufficient in face of the very 

 emphatic results of my own observation, continued dissections 

 forcing on me the desirability of further investigation. I will 

 therefore now give the facts with which I have become acquainted. 



In the common Eed-wing (Turdtis iliacus) the right jugular is 

 very apparent, offering a diameter of one eighth of an inch, while 

 the corresponding vein of the left side needs for its demonstra- 

 tion a very delicate dissection under water, when it may be traced 

 forwards from its point of union with the great transverse trunk 

 at the base of the skull. A safe guide to its homology is found 

 in the accompanying vagus nerve, Figure 1 shows the course of 

 the two veins. 



In the Short-tailed Tit (Parus Iritannictis) this suppression of 

 the left jugular attains the extreme limits compatible with its ex- 

 istence as a vessel, and a lens is necessary to enable one to trace 

 it downwards with the pneumogastric nerve. In one specimen a 

 very fine streak of included blood gave some assistance in deter- 

 mining the presence and course of the tube ; but even it disap- 

 peared at a point about 3 lines above the clavicle. 



Diagrams of cervical blood-vessels in two British birds. 

 Pig. 1. Fig. 2. 



Fig. 1 . The Eedwing ( lurdus iliacus). 



2. The Short-tailed Titmouse {Pants britannicus) -. rj, right, and Ij, 

 left jugular vein ; ca, carotid artery. 



In effect, I concluded that in this bird the left jugular vein is a 



