ANATOMY OP A MONODACTYLOUS FOETUS 



423 



sumed to be one of the ulnar members which has differentiated 

 in spite of the total suppression of the ulna and part of the car- 

 pus. Its appearance at the elbow and not the carpal region 

 lends color to the view that the ulnar anlage of the limb skele- 

 ton never appeared at all even in the early mesenchyme, so that 



Flexor digitoru 

 sublimiS 



Tendon of 

 Flexor digitoru 

 prof und vs 



Text fig. C Outline of the cutaneous distribution of the median nerve in the 

 normal human hand. 



: . Text fig. D Outline of the cutaneous distribution of the median nerve in the 

 left hand of this monodactylous foetus. 



I^The part of the nerve shown in solid black in the two figures, is reckoned as 

 identical in the two^^hands, and is used to determine what single digit is present 

 in the foetus. 



the primary reason for nonappearance of the ulna was not a 

 lack of chondrification and ossification. 



There is another view in regard to this digit, and that is that 

 the digit is really the representative of all five normal ones, 

 being the result of development of the original undivided digital 



