286 



by him in November, 1864. On referring to his note book, I 

 was able to extract the following observation : — 



" Abnormal flexor pollicis longus. — The fleshy origin of this muscle 

 from the bone of the forearm was entirely wanting, and the 

 tendon of the flexor pollicis longns was attached opposite to the 

 base of the 3rd metacarpal bone, to the tendons of the flexor 

 cligitorum profundus, on their superficial surface." 



This remarkable example shows that Man may sometimes possess 

 the arrangement of tendons of thumb and fingers characteristic 

 of the Macaque ; but whether such a case should be regarded as 

 a Macaque passing upwards into a Man, or a Man passing down- 

 wards into a Macaque, or as a congenital freak of nature, I 

 cannot undertake to say. 



In the Cercopitliecus fuliginosus (Cuvier), the tendon of the flexor 

 pollicis longus springs, as in the Macaque, from the central por- 

 tion of the tendon of the flexor profundus that supplies the middle 

 and ring fingers. 



In the Cebus and Lagothrix, a more degraded type of thumb is 

 found ; for the flexor pollicis longus is represented by a tendon 

 to the thumb, not proceeding from the central portion of the 

 tendon of the flexor profundus, but by a tendon which is merely 

 one of the five tendons into which the flexor profundus is divided 

 in the lower animals. 



It is remarkable, however, that among the Quadrumans the most 

 degraded type of thumb is to be found in the so-called Anthro- 

 poid Chimpanzee, for an opportunity of dissecting which, as 

 well as the Negro Monkey, I am indebted to the kindness of 

 Mr. Thomas J. Moore, Curator of the Derby Museum, of Liverpool. 

 In the Chimpanzee, the tendon of the flexor pollicis longus is 

 formed by the union of two small thread-like tendons ; of which 

 one, of silky texture, is derived from the muscle of the flexor 

 sublimis (perforatus), of the index finger; and the other, 

 equally slender, but wanting the silky lustre, proceeds from 

 the tendon of the flexor suUimis of the little finger.* 



* The following remarks on this curious subject, by Professor Gratiolet, will be read 

 with interest by anatomists : — 



" The anatomical examination of this Chimpanzee ( Troglodytes Aubryi) reveals pro- 

 found and really typical differences between man and the most elevated apes. In the 

 latter the thumb is bent by an oblique division of the common tendon of the muscle which 

 bends the other fingers ; it is, therefore, influenced by the common movements of flexion, 

 and therefore is not free. This type is realized in the Gorilla and Chimpanzee; but the 

 small tendon which moves the thumb is in these reduced to a tendinous thread, which 

 exerts no action, for its origin is lost in the synovial folds of the tendons which bend 

 the other fingers, and it abuts on no muscle ; the thumb, therefore, in these apes is 

 wonderfully enfeebled. In none of them is there a. trace of the large independent muscle 

 which gives movement to the human thumb. Far from becoming more strongly deve- 



