40 THE DESCENT OF MAN. 



Many muscles are occasionally developed in man, which arw 

 proper to the Quadrumana or other mammals. Professor Vlaco- 

 vlch" examined forty male subjects, and found a muscle, called 

 by him the Ischio-pubic, in nineteen of them; in three others 

 there was a ligament which represented this muscle; and in the 

 remaining eighteen no trace of it. In only two out of thirty 

 female subjects was this muscle developed on both sides, but in 

 three others the rudimentary ligament was present. This muscle, 

 therefore, appears to be much more common in the male than in 

 the female sex; and on the belief in the descent of man from 

 some lower form, the fact is intelligible; for it has been detected 

 in several of the lower animals, and in all of these it serves 

 exclusively to aid the male in the act of reproduction. 



Mr. J. Wood, in his valuable series of papers,** has minutely 

 described a vast number of muscular variations in man, which 

 resemble normal structures in the lower animals. The muscles 

 which closely resemble those regularly present in our nearest 

 allies, the Quadrumana, are too numerous to be here even speci- 

 fied. In a single male subject, having a strong bodily frame, and 

 well-formed skull, no less than seven muscular variations were 

 observed, all of which plainly represented muscles proper to 

 various kinds of apes. This man, for instance, had on both sides 

 of his neck a true and powerful "levator clavicula," such as is 

 found in all kinds of apes, and which is said to occur in about 

 one out of sixty human subjects.'" Again, this man had "a special 

 "abductor of the metatarsal bone of the fifth digit, such as Pro- 

 "fessor Huxley and Mr. Flower have shown to exist uniformly 

 "in the higher and lower apes." I will give only two additional 

 cases; the acromio-basilar muscle is found in all mammals below 

 man, and seems to be correlated with a quadrupedal gait," and 

 it occurs in about one out of sixty human subjects. In the lower 



"Quoted by Prof. Canestrini in the 'Annuario,' &c., 1867, p. 90. 



M These papers deserve careful study by any one who desires to learn 

 how frequently our muscles vary, and In varying come to resemble 

 those of the Quadrumana. The following- references relate to the few 

 points touched on in my text : 'Proc. Royal Soc. vol. xlv. 1865, pp. 079- 

 384; vol. XV. 1866, pp. 241, 242; vol. xv. 1867, p. 544; vol. xvi. 1868, p. C24. 

 I may here add that Dr. Murie and Mr. St. George Mivart have' shewn 

 in their Memoir on the Demuroidea ('Transact. Zoolog. Soc' vol. vii. 

 1869, p. 96), how extraordinarily variable some of the muscles are in 

 these animals, the lowest members of the Primates. Gradations, also, 

 in the muscles leading to structures found in animals still lower in 

 the scale, are numerous in the Lemuroldea. 



« See also Prof. Macalister in 'Proc. R. Irish Academy,' vol. x 1868, 

 p. 124. 



™ Mr. Champneys in 'Journal of Anat. and Phys.' Nov., 1S71, p. 178. 



