246 THE NATURAL HISTORY RETIEW. 



Tliougli the great liability, in the Negro, to premature obliteration 

 of the sutures in general, and the almost infallible closure of tbe 

 medio-frontal, is insisted upon by French and Grerman anatomists, 

 and anthropologists, no one appears to have pointed out that the 

 posterior division of the median-longitudinal suture, or the sagittal, 

 is especially liable to complete obliteration, both during the foetal 

 and the infantile period. That this, however, is the case, I shall be 

 able to adduce sufficient evidence to prove. It is a just observation 

 of M. Pruner-Bey, that the order of obliteration of the sutures differs 

 according to whether the skull-form is dolicho- or brachy-cephalous ; 

 a law altogether confirmed by the different state of the sutures in 

 the dolichocephalous skulls from the Long, and in the brachycepha- 

 lous skulls, from the Eound Barrows. In the dolichocephalous 

 Negro, as in the dolichocephalous Briton, it may be concluded, (from 

 the researches of AVelcker, on the growth of the cranial bones by their 

 borders), that the special liability of the median-longitudinal (frontal 

 and sagittal) sutures to obliteration, is due to the opposed suture 

 margins coming sooner into contact than in brachycephalous peoples, 

 in consequence of the growth of the brain being chiefly in the lon- 

 gitudinal, and much less energetic in the transverse and vertical 

 directions. In addition to this anatomical cause, it may be sur- 

 mised, as pointed out at the meeting at Bath, by Dr. John Davy, 

 that physiological influences may contribute to the same result, and 

 that a tendency to exuberant ossification may be produced in the 

 Negro as also (it may be added) it may have been in the Ancient 

 Briton, by a diet of a highly animalized nature, consisting chiefly of 

 milk and flesh. 



It is concluded that in order that synostosis of the cranial bones 

 should be the cause of any peculiar form of the skull, it must be 

 one of two descriptions. Either it must be of intra-icterine origin, 

 when it is most efficient in the production of monstrous, or terato- 

 logical forms ; or infantile, and occur during the period of growth 

 and development; when it produces deviations more moderate in 

 extent, though still abnormal.* By the ossific union of the two 

 parietal bones, and consequent efliicement of the sagittal suture in 

 foetal life is produced that very abnormal skull-form, now known as 



* As Dr. Humphry observes, " After indigitation (of the sutures) has taken 

 place, the interlocking of the bones is so intricate that I question whether gi-owth 

 can take place at their edges much more easily than in other parts of their ex- 

 tent." loc. cit. p. 190. 



