PRESENT PROBLEMS OF MYOLOGICAL RESEARCH AND THE 
SIGNIFICANCE AND CLASSIFICATION OF 
MUSCULAR VARIATIONS.’ 
BY 
GEO. 8. HUNTINGTON. 
From the Anatomical Laboratory of Columbia University. 
With 7 COLORED PLATES. 
The study of comparative myology and of myological variations im- 
presses three facts of cardinal importance on the observer: 
1. Forms, which according to the zoological system commonly ac- 
cepted are widely separated from each other in the series, present in 
some details of their myological structure identical or very closely allied 
characters. 
2. Human muscular variations and supernumerary muscles are fre- 
quently homologous with muscles normally occurring in species appar- 
ently very far removed from man in the zoological scale. 
3. Within the confines of a more limited group, as a single mam- 
malian order, the smaller subdivisions of family and species are at 
times sharply differentiated from each other in some detail of their 
structure, which distinguishes the form possessing it from the remain- 
ing divisions of the group, no matter how close in other respects their 
morphological congruence may be. 
The concurrence of a structural character, or its occasional recur- 
rence by variation, in species which in other respects have little in 
common, necessitates a very careful revision of its development, deriva- 
tion and functional significance in order to avoid erroneous conclu- 
sions respecting the phylogeny of the species in question. 
The further the study of comparative myology is carried, and the 
more complete our knowledge of this science and of human muscular 
variations becomes, the clearer does the fact appear that, with few 
exceptions, the living mammalia present in their muscular system very 
complicated conditions. These are, in many forms, the result of 
1Read at the Fifteenth Session of the Association of American Anatomists, at 
Chicago, Ill., December 31st, 1901, to January 2nd, 1902. 
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