FONTANELLA METOPICA IN AN ADULT SKULL 269 



mm. of the nasion. In three other cases the great fontanelle 

 reached within 22 mm. of the nasion. This prolonged arm of 

 the great fontanelle is an extreme variation, and is not necessarily 

 a result of hydrocephalus. In the skull of a year old hydrocephalic 

 negro, the author found the great fontanelle reaching to within 16 

 mm. of the nasion; in contrast to the cases in figure 4, however, it 

 was, even at its lower end, 17 mm. wide; in the middle of the 

 frontal arc 29 nun. and at its upper end 35 mm. It is striking 

 that the lowest portions of the frontal bones always approximate 



Fig. 5 Norma verticalis of a skull of erethizon dorsatus with fontanelle 

 bones. 



each other and indeed to a height which is considered typical 

 for the position of the metopic fontanelle, that is, to a point to 

 which the frontal arm of the great fontanella may extend un- 

 interrupted or constricted. As a designation for the lowest 

 portion of such long bregmatic fontanelles extending into the 

 nasal third of the frontal arc, the name fontanella metopica may 

 well be retained. However, no fundamental difference is to be 

 made between the two mentioned fontanelles. It is more fre- 

 quent for the lower end alone to remain patent in children and 



THE AMERICAN JODRNAL OP ANATOMY, VOL 23, XO. 2 



