CEAJS^IOMETBT AND CRANIOOEAPHT, 357 



H, H, is the horizontal line of the cranium, 

 w, marks the maxillary radius. 

 n, „ fronto-nasal „ and tranverse arc. 



/, „ frontal „ and „ „ 



V, „ vertical „ and „ „ 



p, „ parietal „ and „ „ 



0, „ occipital „ and „ „ 



B, B, shows what may be termed, in contradistinction to 

 the horizontal, the basal line of the cranium, or, more 

 properly speaking, of the cerebrum : it is a line drawn 

 in the direction of a plane, extending from the level 

 of the occipital spine to that of the glabella. 

 Pig. 2. Ip marks the direction of the longitudinal vertical plane ; 



zz that of the zygomatic breadth. 

 Fig. 3. hk, corresponding to Ip in Fig. 2, marks the direction in 



which the height of the cranium is taken. 

 Eig. 4. Ip, longitudinal vertical plane ; 



tp, transverse vertical plane. The intersection of these 

 lines is the vertex. 

 Fig. 5. Ij} and tp signify the same as in Fig. 4, and their intersec- 

 tion, nearly at the middle of the anterior margin of 

 the Jvramen mar/num, of course corresponds with the 

 vertex above, the distance between the two points 

 being the height of the cranium. 

 Having obtained these measiu-es, the next question is, what is to 

 be done with them ? In the first place, they afibrd the means of 

 rovighly estimating the absolute dimensions of any cranium as com- 

 pared with another ; and secondly, they aUow of our using precise 

 numerical values, in place of words, in speaking of the comparative 

 proportions of difterent classes of skulls ; that is to say any term so 

 employed may and ought to be associated with a given numerical 

 value. 



An idea of this kind appears to have been entertained by Prof v. 

 Baer, who seems to have been the first to express the proportions or 

 some of the proportions of a cranium in terms of a common module 

 — that chosen by him being the length, and in this we have followed 

 him. It will readily be seen that by the adoption of this plan, the 

 comparative length, or shortness, or height, or any other dimensions 

 of a cranium may be accurately expressed in figures. As, for in- 

 stance, assuming the length as the standard or modulus, crania, as 

 regards their breadth or height, may be said to have it .6, .7, .8 or .9 

 of the length — the two former numbers actually embracing pretty 

 nearly all the crania hitherto classed as dolicocephalic, whilst under 

 the two latter will be found included all or nearly aU the so-termed 

 brachy cephalic skulls.* By reference again to the same module, the 



* M. Broca also (Bull, dc la Soc. d'Anthrop. July 1861,) proposes to take, as 

 " iudice cephalique," the proportion of length to breadth ; and, as we think very 



