124 THE NATIJEAL HISTORY REVIEW. 



of the forehead above the eyebrows and orbits, the comparative 

 breadth across the parietal region, so that the norma verticalis ap- 

 proached the triangular form, (the apex at the forehead, the rounded 

 base at the occiput,) were well marked, and showed their close alli- 

 ance to the boy's head I have just described. The two new-born 

 children examined by Welcker, had both hare lips and cleft palates, 

 but in none of the other cases did such malformations exist. In 

 several of the cases also he noticed that the eyes, owing to the 

 diminished breadth of the inter-orbital space, were more closely set 

 together than is usual. In my case this peculiarity was but slightly 

 marked. 



Two theories may be advanced, to explain the production of this 

 description of cranial malformation. 1st. That the frontal bone had 

 only possessed a single ossific centre, situated in the middle line. 

 2nd. That it had in the usual manner two primary ossific centres, 

 but that these, instead of remaining distinct and separated from each 

 other, had very early become blended together, so as to form in the 

 middle line the projecting beak, so characteristic of this form of 

 cranium. Along with Welcker I am inclined to support the latter 

 theory. Eor I believe, that, if the first named mode of develop- 

 ment had occurred, a much greater amount of deformity would have 

 been occasioned, than is exhibited by these crania, and that a Cyclo- 

 pian or other monstrous form of head would have been produced. 

 If the second of these two theories be accepted, then these Trigone - 

 cephali are, as regards the principle which regulates their mode of 

 production, closely allied to those Scaphocephali already alluded to, 

 in which, as has been contended by Yirchow, Welcker, and myself, 

 the lateral compression of the cranium in the parietal region, is due 

 to a premature blending of the ossific centres of the two parietal 

 bones, and a consequent obliteration of the sagittal suture. The 

 head of the boy whose case I have detailed, supports the view that 

 this premature blending of the two originally distinct halves of the 

 frontal bone, took place at a period of foetal life, some time before 

 the termination of intra- uterine existence, for if the statement of the 

 mother is to be trusted, there was a complete absence of the fonta- 

 nelle at the time of birth. It does not necessarily follow, however, 

 that this intra-uterine closure of the anterior fontanelle is a constant 

 occurrence in these cases, for in the heads of the two new born 

 children, figured by "VVelcker, the anterior fontanelle is open, and in 

 the head of one of the 5-year old children, a distinct anterior fonta- 

 nelle bone existed. 



