GENETIC TYPE AND THE ENDOCRINES 281 



versely and is seen as a shortened ovate when viewed from 

 the top. We have already seen that the basicranial pattern 

 is closely the same for both these skulls. 



The cranium in the achondroplasic skull (fig-. 1) is shorter 

 and somewhat wider than in the long skull, thus making its 

 cranial index apparently high. When we recall, however, 

 that the base of this skull is strongly arched upward, as 

 illustrated in the outlines in text-figure 64, and that the lower 

 parts of the occipital and frontal regions must, as a result 

 of this, be brought closer together with consequent anteropos- 

 terior shortening of the cranium (clearly shown in this figure) 

 it becomes evident that this skull may be primarily of dolicho- 

 cephalic tendency. If we imagine the skull to be plastic so 

 that the lower occipital and frontal regions could be lifted 

 and pulled farther apart in the sagittal plane, the exaggerated 

 arch of the basicraninm would be flattened and the cranial 

 length increased by this force, thus giving an approach toward 

 the dolichocephalic pattern. The achondroplasic specimen 

 may have had dolichocephalic ancestry, and had it been able 

 to develop normally its cranial index would have been quite 

 low. 



The peculiar modifications in the adult bulldog typed skull 

 are largely the consequence of definite alterations in the 

 development of the cartilaginous structures forming the basi- 

 craninm. In the normal immature human skull, there is a 

 thick epiphyseal growth cartilage separating the anterior 

 surface of the basioccipital bone and the posterior surface 

 of the basis] thenoid bone. This cartilaginous plate is the 

 most important element in producing the increase in length 

 or forward growth of the basicraninm, and this growth in 

 turn accentuates the growth of the vomer and nasion, stimu- 

 lating the development of a high nasal bridge and a strong- 

 forward growth of the face leaving behind a vertical or re- 

 ceding, but not bulging, forehead. The prominent growth 

 of the nose is also closely correlated with the forward ex- 

 tension of the maxilla. 



