Robert Beuuett Bean 



305 



While numerous variations in the origin and distribution of the 

 branches of the artery are observed in my study, it is nevertheless pos- 

 sible to classify the cases, for they are found to fall naturally into a num- 

 ber of distinct types. In section A of this work it is proposed to describe 

 these types. This will be followed in section B by a description of the 

 origin and distribution of the individual branches, while in section C the 

 results of the present study will be discussed in their relation to the 

 previous work upon the subject, and illustrative tables will be appended. 



AC.R 



RD.TjC. 



tp- 



FiG. 2. Type I, occurring in S0% of the specimens, 22^ on the right side, and 

 S% on the left side of the body. For index to lettering see Fig. 1. 



The three divisions of the subclavian artery referred to throughout this 

 work are: Part I, that portion medial to the scalenus anticus muscle; 

 Part II, posterior to it; and Part III, lateral to this muscle. 



The records given are from 74 male Negroes, 16 female ISTegroes, 21 

 male Caucasians and 3 female Caucasians. The race and sex are not 

 determined in 15 subjects. The Negroes are the American variety, and 

 possibly all of them have a trace of the Caucasian mixed with the Negro, 

 the proportion in an}^ case being uncertain. 



