Page 471. 
176 THE CAROTID ARTERIES OF BIRDS. 
IMPENNES. 
Both carotids are present in these birds.’ 
Species ewamined. 
Spheniscus demersus. Aptenodytes pennantit. 
humboldtii. ; 
CRY PTURI. 
Both carotids are present in these birds. 
Species examined. 
Rhynchotus rufescens. Crypturus sallei. 
STRUTHIONES. 
Both carotids are present in 
Struthio camelus, 
The left carotid alone is present in 
Rhea americana. 
Both carotids are present in 
Oasuarius bennettit. Dromeus nove-hollandie. 
bicarunculatus. 
The left carotid only is present* in 
Apteryx mantelli. Apteryz owenii. 
In reviewing the above facts, for the purpose of forming an esti- 
mate as to the significance in classification of the arrangement of the 
carotid arteries in birds, the following conclusions may be drawn, if 
the Psittaci be omitted from consideration, which, from the great 
peculiarities they present among themselves, it will be better to do at 
present :— 
1st. In many cases the uniformity of the carotids is of ordinal im- 
portance, all Passeres possessing the left carotid only, whilst both are 
present in all Columbex, Anseres, Gralle, and Accipitres. 
2nd. As a family character, the distribution of the carotids is very 
suggestive, in some cases presenting a well-marked difference between 
* In his “ Anatomy of Vertebrates” (vol. ii. p. 199), Prof. Owen remarks :— 
“In the Apteryx I found that the left carotid alone passed to the usual place in 
the neck, and divided at the third cervical vertebra, to supply the head in the usual 
way.” But in the original memoir on the bird (“Transactions of the Zoological 
Society,” vol. ii. p. 278) the same author has stated that both are present, which is 
not the case in the specimens examined by me. 
