144 HEREDITY IN RELATION TO EUGENICS 



Fig. 119. — Case of harelip at one year of age. R. W. Murray, "Harelip 

 and Cleft Palate," 1902. 



a second case of insufficient enamel together with failure 

 of some teeth to erupt. In these cases the abnormal con- 

 dition seems to be due to some additional factor, inhibiting, 

 as it were, the normal development of the enamel. 



There is a close relation between the form of the jaw and 

 peculiarities of dentition. That the form of the jaw is in- 

 heritable is nicely shown in figure 118. 



e. Harelip and Cleft Palate. — These are intimately asso- 

 ciated deformities, due to a more or less complete failure 

 of the foundations of the upper jaw, which are paired, to 

 grow completely to the middle line of the roof of the mouth. 

 If the failure to close is in front harelip results, if behind 

 cleft palate or merely cleft uvula. Occasionally both cleft 

 palate and harelip may be present (Fig. 119). 



A number of fairly extended pedigrees have been pub- 



