OSTEOMETRY; THE MEASUREMENT OF THE BONES 57 



4a. Basion-bregma height; this should correspond within about the 

 same limits as the previous one. 



[The correspondence of these two lines, placed nearly at right angles 

 to each other, in both craniogram and in the skull by direct measurement, 

 will usually establish the practical correctness of the former. Where, 

 however, the special accuracy of a particular region is desired, use may 

 be made of other lines, such as the nasion-basion, or the basion-prosthion, 

 if the discussion especially concerns the facial region; or in the chords 

 and arcs involved, while investigating a profile contour.] 



2. Important Lines . 



The most of these may be taken also direct, and hence have already 

 found a place upon the previous list. Many, however, serve here in the 

 construction of some important angle; as a base for some special perpen- 

 dicular; or otherwise in some special relation, which makes it convenient 

 to designate them by other names. These new names are given here, 

 but the lines themselves may be recognized by their numbers, which are 

 the same as in the previous list. The old names also are added in 

 parenthesis, (cf. Figs. 26, 27, 28). 



33. The calvarial base (nasion-inion line). This line serves as the 

 base upon which the calvarial height line [48] is erected. 



9. Cranio-basal length (nasion-basion line). This line serves as the 

 entire length of the basis cranii, from the anterior edge of the occipital 

 foramen, forward to the anterior limits of the skull. Few people, even 

 anatomists, realize to how great an extent the axis of the human skull 

 has become shortened and bent together; bringing the occipital foramen 

 almost in contact with the posterior nares, and placing it about in the 

 center so that the heavy head, in the erect position of the body, is almost 

 balanced upon the top of the vertebral column. 



10. Facial depth (prosthion basion line). 



34. Inferior facial depth (gnathion-basion line). As the gnathion 

 properly lies underneath the jaw, where it serves as the limit for lines of 

 measurement coming from the direction of the nasion, it is more natural 

 to draw this, line, from the basion, not to the gnathion, but to the most 

 anterior point of the jaw, which is about at the pogonion. It may be 

 possible ultimately to remedy this inconvenience, even to the establish- 

 ment of a new landmark, between pogonion and gnathion, but at present 

 the gnathion is the point spscified, and one should be careful to use it, 

 bringing the termination of the Inferior facial depth line, and that measur- 

 ing the total facial length [11] to the same point. 



12. Superior facial length (nasion-prosthion line). [This line, taken 

 with that of the superior facial length and the cranio-basal length, forms 

 an important triangle, which is practically coincident with the nasal 

 cavity. This may be found of importance in the future study of the 



