OBLITERA.TION OF SUTURES IN SKULL 499 



fact that the masto-occipital suture belongs to those persisting 

 the longest. 



Now it is important to note that this author had at his dis- 

 posal only a small number of skulls of 20 to 30 years and that 

 his investigation was made principally on adult skulls. If the 

 investigator had extended his examination upon a sufficient 

 number of non-adult skulls, his conclusion would, no doubt, 

 have been quite different. For the coalescence of the occipital 

 and petrosal bone in the skull of infants is not at all a rare 

 event. On the contrary amongst my material there even was a 

 considerable and unexpected number of skulls, showing complete 

 or partial closure of the masto-occipital suture, either on one side 

 or on both. Moreover not in all cases was the coalescence 

 restricted to this one suture, but in a large number of skulls 

 two or three or even four sutures were totally or partially obliter- 

 ated. Here I wish to treat separately the cases in which only 

 the masto-occipital suture was closed and in which the oblitera- 

 tion was of a more extensive nature. I will begin with the 

 first group. 



It is scarcely necessary to particularly mention that in case 

 of closure of the masto-occipital suture the coalescence of the 

 two bones can be a total or a partial one. In the second table 

 this fact is taken into consideration. As a rule the coales- 

 cence of the petrosal and occipital bones begins midway in the 

 suture, passing in the majority of cases from this point towards 

 the masto-parietal suture, in consequence of which, in a partial 

 closure, it is most often the upper half which is obliterated. 

 Table 2 shows the results of my examination on the masto- 

 occipital suture. This table demonstrates at once the quite 

 unexpected fact, that in the human non-adult skulls the masto- 

 occipital suture is found closed so often, that one is inclined 

 to consider this phenomenon no longer as an anomaly. Let us 

 consider the frequency of this obliteration. It is not possible 

 to recognize, with the aid of table 2 (p. 500), the absolute num- 

 ber of skulls in which the suture showed obliteration, a certain 

 number being twice mentioned, viz. the skulls entirely closed 

 on the one side and partially on the other; the skulls in which 



