279 



but a narrow strip of bone between the border of the foramen 

 magnum and this open defect. All the basicranium in front 

 of this opening is entirely basisphenoid bone. The oral sur- 

 face of the palate in this skull is convex both transversely 

 and anteroposteriorly, a direct contrast to the normal skull 

 which is concave in both these directions. The entire palate 

 is abnormally short. This skull also differs from the other 

 two shown in that the zygomatic arch is short and sharply 

 curved in a lateral direction. 



Cranial index 



100 



72.58 



80.79 



Normal 



Achondroplasic 



Text-figure 64. Sagittal outlines of the three human skulls shown in plate 51. 

 These outlines are based on measurements of the straight distances from the 

 auditory meatus to the points designated, a, superior dental alveolus; b, anterior 

 nasal; c, nasion; d, bregma; e, occipito-parietal suture; f, occipital protuberance; 

 g, posterior margin foramen magnum; h, anterior margin foramen magnum; j, 

 base of vomer; k, posterior palate; x, auditory meatus. 



In text-figure 64, comparable outlines of these three human 

 skulls are shown. These outlines were determined by measure- 

 ments of the straight distances from the auditory meatus 

 to designated points along the sagittal border of the skull, 

 and the outlines of the skulls have been superimposed as 

 nearly as possible. In the outlines comparing the three skulls, 

 the long skull is indicated by a dot-dash line, the round skull 

 by a dashed line and the bulldog typed skull by the solid 

 line. The positions of the foramina magna in the sagittal 

 plane are indicated by the three spindleform outlines at the 



