VENOUS SYSTEM OF BIBBS. 533 



mere rudimentary structure, physiologically valueless, while at the 

 same time the full morphological equivalent of the vein of corre- 

 sponding name on the dextral side. Eig. 2 depicts the appearance 

 presented by my dissection ; and, as in the former diagram, there 

 is noticeable a peculiar lozenge-shaped space between the two 

 branches of the divided single carotid artery. This is existent, 

 too, in all the birds, so far that I have examined, in which occurs 

 the peculiar suppression of the left jugular vein, although in some 

 the bifurcation is more nearly in. relation with the great trans- 

 verse venous trunk than in others. 



With these facts before me, I was advised by Dr. Eolleston, to 

 whom I gratefully express my indebtedness for much valuable as- 

 sistance and unceasing kindness, to consult tlie memoir by 

 Neugebaur contained in the * Nova Acta,' vol. xxi., and entitled 

 ' Systema venosum Avium cum eo mammaliuui, et imprimis ho- 

 minis, collatum ;" and in this little-known but exhaustive and 

 pains-taking paper I found the following passages. (Before pro- 

 ceeding to quote, I may say I took occasion to verify the references 

 to Barkow's own papers.) 



" Barkow has three laws concerning the relative thickness and 

 the presence of the jugular veins in birds : — 



" 1. A single jugular vein exists on each side of the neck, the one 

 equal with the other. 



" 2. There is one on each side, of which one is greater {fortior') 

 than the other. Or, lastly, 



" 3. One side only is provided with a jugular vein, the other has 

 none (alterum nulla).'''' 



Neugebaur, commenting on these rules, ventures to distrust the 

 truth of the third, and imagines that instances adduced will fiiU 

 under the second rule. In this connexion I much regret tliat I 

 am unable to speak concerning the four species of Woodpecker 

 {Pious martius, P. viridis, P. major, P. medius) with which Neu- 

 gebaur associates Rathke as holding a view opposed to his own ; 

 and I shall be grateful to any one who will supply me with speci- 

 mens of these birds. The Great Spotted Woodpecker (P. major) 

 and P. minor (the Lesser Spotted Woodpecker) are said by Tarrell 

 to frequent the neighbourhood of Keusington Gardens ; but P. 

 martius (the Great Black Woodpecker) is rare in this country, 



Neugebam*'s words on tliese birds are as follow : — "Quod de- 

 nique attiuet ad regulam tertiam, mihimet non contigit, ut avem 

 uUam singula tantum vena jugulari jjraxlitain iuveuerim, et 



