EXPKESSION IN THE JAW. 191 



Depression of the jaw elongates the face. 



We will now look at some examples of expression 

 in the permanent and unchanging conditions of the 

 head size, form, conditions of development. There 

 are certain defective developmental conditions seen 

 about the head which are not uncommon accompani- 

 ments of defect of brain, and which therefore 

 express, though with a considerable degree of 

 uncertainty, the probability that the brain may be 

 defective in its powers. * The following head 

 peculiarities are pointed out by Dr. Shuttleworth : 

 " Congenital idiots have often peculiarities of con- 

 formation of head or feature which bear the im- 

 press of original defect. A shelving forehead, a 

 flattened occiput, a notable proportion as to size 

 between head and body as in microcephally (small- 

 headed idiots), a nut-shaped forehead as in scapho- 

 cephally, marked obliquity of the supra-orbital 

 ridges, absence of the nasal bones, and a lamboid 

 (A-shapen) vaulting of the palate, are some of the 

 cranial peculiarities associated with congenital 

 forms of idiocy. We shall see also that the osseous 

 irregularities in the form of the hands and feet, 

 fissures and hypertrophy of the papillae of the 

 tongue, and a coarse, sometimes branny epidermis, 

 are diagnostic marks of one congenital variety. The 

 external ear is often unshapely, planted low down 

 and comparatively far back ; the angle of the jaw 

 is more obtuse in congenital idiots than in normal 

 children." 



Summary. In this chapter certain modes are 

 * See laws of proportional development, chap, xviii, 



