32 L. BOLK 



comparing the average index cephalicus in normal and metopical 

 skulls. In doing so the following averages were found. That 

 of the total number of 1400 skulls amounted to 78.3 and that of 

 the 134 metopical skulls, 78.9. This difference is such an in- 

 significant one that it does not prove anything as to a sup- 

 posed more brachy cephalic character of metopical skulls. And 

 the average index cephalicus is such a low one that it by no means 

 justifies the opinion that brachycephaly is a characteristic of 

 metopical skulls, or that metopism in general is favorable to the 

 formation of brachycephalic skulls. 



Finally I wish to advance still another proof of the absence 

 of any relation between the shape of the skull and the persistence 

 of a frontal suture. Among the 1400 skulls there were 23 with 

 the very low index cephalicus of 71, an indication of a very nar- 

 row skull. And among the 134 metopical skulls, five were found 

 with the mentioned low index. This fact demonstrates clearly 

 that metopism occurs even frequently in skulls which are doli- 

 chocephalic in high degree. 



It is well known that for the characterization of a skull its 

 index cephalicus is a very insufficient indicator, because for 

 instance the height of two crania with quite the same index can 

 differ considerably, or the curvatures of the calvarium can be 

 very dissimilar. And finally this index furnishes not a single 

 indication as to the absolute dimensions of the skull, a very 

 large and a very small skull may have an equal index cephalicus. 

 Hence a comparison of this index in regard to persisting metop- 

 ical sutures is a very insufficient means of recognizing the ex- 

 istance of an eventual relation between the shape of the skull 

 and the frequency of metopism. It is necessary to prosecute 

 our investigation in still another direction. 



First we will examine whether the three principal dimensions 

 of the skull in average are different in normal and metopical 

 crania. A comparison of the sum of these averages in both 

 groups of skulls will enable us moreover to answer the question 

 whether it is true that metopical skulls commonly are larger, 

 including a heavier brain than nonmetopical crania. 



