Differentiation. 283 



pliin. The commonest variation of the aortic arch is where the innomi- 

 nate gives off the left carotid as well as the right, and so supplies both 



FIG. 114. Four specimens of Human Anom- 

 alous formations of the aortic arch and its 

 branches. 



re, lc. Right and Left carotid arteries, go- 

 ing to the head. 



r.s, /.s. Right and left subclavian arteries, 

 going to the arms. 



i. Innominate artery. 



sides of the head ( See Fig. 114 A), 

 the artery supplying the left arm 

 coming off as usual. This is the nor- 

 mal condition in Apes, Bears, Dogs, 

 and all the feline tribes ( Lion, Tiger, 

 Cat, Leopard, &c. See fig. 115 D). 

 In some rare cases in man one branch 

 only comes off from the aortic arch, 

 and this a^ain divides into the various 

 arteries supplying the head and arms. 

 In Horses and other solipeds, we see 

 this form of aortic arch. (See fig. 114 D and 115 A.) Again, the 

 branches may all be given off separately from the arch, as is the arrange- 



FIG. 114. 



FIG. 115. 

 Fir,. 1 16. Origin of Arteries from Aortic Arch in sonic Mammals. (Owen.) 



A.- Ox. B.-Latn;.. C.-ClininV. 



I) -Lion. E. Otter. F. Gibbon. 



(}. Hedgehog. H. Man. I. Dugong. 



a.- Main Aorta, [refcrciiccs same in all. 



&. " Anterior Aorta " of Veterinarians or " innominata " of hninan anatomy. 



c. Right Carotid artery. c 1 the left. 



d. Brachial artery to the right arm ). d 1 



V. ' Vertebral artery, or right Thoracic v' 



ment in the Walrus.'' ( See Fig. 114 C. ) "1 have three limes met 



