PHYSICAL CHARACTERS IN MAN 105 



extra little toe on each foot. The extra digits were 

 all perfectly formed, with nails and three phalanges. 

 The father also was hexadactylous, having five 

 metacarpal bones, but six metatarsals. The pedigree 

 of this family through four generations is given in 

 Fig. 18. Beside each is given (above) the number 

 of fingers and (below) the number of toes. The in- 

 heritance is strictly that of a Mendelian dominant, 

 with occasional failure of one hand or foot to exhibit 

 the abnormality. 



In another hexadactylous famil}^ (Sedgwick, 1863, 

 p. 188) an extra finger with two phalanges and a nail 



f 



xO 



o^ 



'xn 



ixo 



i 



i 



6.6 



6.6 



I 



6.5 



W~^^ 



66 66 



Fig. 19. — Hexadactylous Family. 



was attached to the base of the first phalanx of each 

 little finger. The condition was followed through 

 four generations. There was some variation in its 

 expression, and it skipped two generations both in 

 the male and the female line (see Fig. 19). 



Schroeder (191 8) described a condition of hypo- 

 dactyly appearing in the hands and feet of a family 

 for five generations and accompanied by other 

 deformities. The strain originated with a woman, 

 who is said to have had normal parents. She j^ro- 

 duced three affected and two normal children, the 

 latter having only normal .descendants, while the 



