CHAPTER XX. 



THE CORRESPONDENCE BETWEEN THE BONES OF THE ANTE- 

 RIOR AND POSTERIOR EXTREMITY AND THE MODIFICA- 

 TIONS OF THE POSITIONS OF THE LIMBS. 



That a general correspondence exists in the plan of con- 

 struction of the anterior and posterior extremity cannot fail 

 to strike the most superficial observer, though to follow out 

 this correspondence into all its details has severely exercised 

 the ingenuity of many an anatomist. 



It would be quite beside the character of the present 

 work to give an historical account of the numerous and 

 very various views which have been held upon this sub- 

 ject, 1 but I propose to lay before the student in a con- 

 densed form such portions of the general outcome of these 

 researches as appear to be most satisfactorily established, 

 premising, however, that all the statements hereinafter to 

 be made have not yet met with universal assent. 2 



1 For the bibliography of this question, see Mivart " On some Points 

 in the Anatomy of Echidna hystrix " (Linn. Soc. Trans, xxv. 1866) ; 

 and Rolleston " On the Homologies of certain Muscles connected with 

 the Shoulder Joint" {Ibid. xxvi. 1869). See also Humphry's "Ob- 

 servations in Myology," 1872. 



2 For an exposition of the very opposite hypothesis of "Antero- 

 posterior Symmetry,'" see Jeffries Wyman " On Symmetry and Homo- 

 logy in Limbs" {Proc. Boston Soc. Nat. Hist., June, 1867, p. 277) ; and 

 the elaborate series of papers by Dr. Elliott Cones, published in the 

 Medical Record (New York) for 1870. 



