FONTANELLA METOPICA IN AN ADULT SKULL 267 



showed the metopic fontanelle to be present in two idiots, one of 

 them a microcephahis with a skull capacity of only 704 cc. 

 Schwalbe in his explanation makes use of the hypothetical sup- 

 position that the tubera frontalia might consist of two adjacent 

 ossification centers, which usually join immediately, but in ex- 

 ceptional cases remain separate, later forming two independent 

 systems of lines of ossification. The divergence of these lines 

 forms the metopic fontanelle, which in children is situated on a 

 plane with the tubera frontalia. Schwalbe emphasizes the fact 

 that the metopic fontanelle and its derivatives are always found at 

 a definite location, while the fontanelles and fontanelle bones 

 which are found at times in the upper portion of the frontal suture 

 have a more variable situation and are to be included in the great 

 fontanelle. Schwalbe cites among other the cases described by 

 Staderini, in which the fontanella metopica is connected with the 

 great fontanelle by a wide space. In spite of this, however, he 

 makes a distinction between the two above mentioned fontanelles, 

 which rests purely upon the situation of the metopic fontanelle. 

 According to Schwalbe in children up to 13 months the latter 

 varies in respect to the lower end of the fontanelle from 5.6 to 

 17.8, in respect to its middle point from 11.2 to 22 per cent of the 

 frontal arc above the nasion. Fischer described the skulls of 

 two children in which interfrontal fontanelle bones are divided 

 in two and in three partfe respectively. In one of these the mid- 

 dle point of the fontanelle bone was situated 30.6 in the other 

 50 per cent of the frontal arc above the nasion. 



It is evident that the position of the metopic fontanelle is not 

 as definite as claimed by Schwalbe, who makes the following 

 statement : 



In the rare cases in which two or even three groups of Wormian bones 

 occur in the frontal suture, only the lowest corresponds to the normal 

 medio-frontal fontanelle; those situated near the parietal bones, how- 

 ever, are to be considered as Wormian bones in an abnormally wide 

 suture (hydrocephalus). The latter may even represent the anterior 

 end of the large fontanelle, which has extended abnormally far into the 

 frontal region. It sometimes occurs that the anterior end remains open 

 for a longer period than that portion lying directly posteriorly; there- 

 fore the anterior end may become separated as a secondary fontanelle. 



