A Method of Craniometry for Mammals. 47 



of the difficulty of fixing a point on the actual cranial wall 

 which can be taken in all cases. The difficulty may be 

 surmounted by using the outermost points of the articular 

 surfaces for the mandible as the extremities of a diameter 

 (Fig. 3, a). Although this does not bear a very constant rela- 

 tionship to the actual breadth of the cranial cavity, it has at 

 least the advantage that it expresses the width of the head. 



Height of Cranium. — Because of the marked difference in 

 the shape of the cranium of man and the rest of the 

 mammals, it is not sufficient to indicate its height by the 

 one diameter employed by anthropologists. Two are 

 obviously needed. One of them corresponds to the " height 

 of cranium" of anthropology, and is taken between the 

 basion and the bregma. This may be called the ohlique 

 height because of its direction ; the bregma lying in front 

 of the basion — markedly so in some animals (Fig. 4, e). 

 The other "height" diameter, it is suggested, should be 

 taken between the basion and the lambda ; and, because this 

 is speaking generally, vertical in direction, it may be known 

 as the vertical height, in order to distinguish it from the 

 basi-bregmatic diameter (Fig. 4, f). 



Bistephanic Diameter. — The extent of the temporal fossa 

 being so variable in the different orders of mammals, and even 

 in the members of the same order, the distance between the 

 two stephanions is one which one cannot afford to neglect. 



Frontal and Fronto-parietal Lengths. — The length of the 

 frontal bones (bregma to nasion), and that of the combined 

 frontal and parietal bones (lambda to nasion), will be found 

 to be very variable quantities (Fig. 4). These lengths may 

 be estimated by means of a tape-measure laid along the 

 sagittal suture. It may be remarked that these are the 

 only measurements made by means of a tape, all the others 

 being arrived at by the use of calipers. 



Length of Face. — The majority of anthropologists express 

 the length of the face in a measurement taken from the 

 mid-point of the bistephanic diameter to the point of the 

 chin. This is not convenient for the Mammalia in general, 

 first, because the Stephanie diameter is often very far 

 removed from the region of the face ; and secondly, because 



