52 STEUCTUKE AND CLASSIFICATION OF BIRDS 



The arterial system of birds ' is chiefly remarkable for the 

 large number of the different arrangements of the carotids. 



FiQ. 32. — Normal AvUN CAKOiibs. 



3'.c, Z.C, carotids ; r.s, l.s, subclavians ; r.i, ZJ, 

 right aud left innominate j a, aorta ; A, 

 il'-s origin. (Tliis and five following figs, 

 after Gabbod.) 



Fig. 33.— Cakotids of Bittebn. 



LteTTEBING AS IN FiG. 32. 



(^ 



Fig. 34. — Cabotids of Flamingo. 

 Letteeing as in Fig. 32. 



Fig. 35. — Cabotids op Cacatua. 

 Letteedjo as in Fig. 32. 



Many writers, especially Nitzsch, among the earher anato- 

 mists, have drawn attention to some of these variations. 



' L. A. Neugebaueb, ' Systema Venosum- Avium,' Nov. Act. Acad. Nat. Cv/r. 

 xxi. 1845, p. 517 ; Bathke, ' Ober die Carotiden . . . der Vogel,' Arch. f. Anat. u. 

 Phya. 1850, p. 184, and ' Bemerk. iiber die Entstehung, &o., der gemeinsoh. 

 Carotis,' ibid. 1858, p. 315 ; Gabbod, 'On the Carotid Arteries of Birds,' P. Z. S. 

 1873, p. 457 ; C. H. Wade, ' Notes on the Venous System of Birds,' /. Linn 

 Soc. xii. 1876, p. 531 ; F. Hochbtettee, ' Beitrage zur Entwioklungsgeschiohte 

 des Venensystems,' &c., Morph. J.B. xiii. 1888, p. 575, and ' tJber den 

 Ursprung der Subclavia d. Vogel,' ibid. xvi. 1890, p. 484. 



