3^4 



THE AMERICAN NATURALIST. [Vol. XXXVIIl. 



B. I. A human foetus/ of white parents, born at term, 

 ninth pregnancy. The child weighed three pounds and lived 

 four days. Whole skeleton highly rachitic. 



Both of the parietals, besides other bones of the skull, show 

 considerable modification. (Figs, i and 2.) 



The left parietal is divided into two by a narrow and some- 

 what irregular membranous space running antero-posteriorly, 

 very nearly parallel with the line of. the sagittal junction, which 

 is also membranous. The upper portion is slightly higher than 

 the lower, its maximum height, measured by a tape, being 4.2 

 cm., while that of the lower piece is 3.8 cm. 



The anterior third of the dividing space is very wide, forming 

 a large fontanel, and this is filled with one large and one smaller 

 secondary bones. Posterior to the two portions of the parietal 

 and between these and the occipital, from the sagittal line to the 

 mastoid, is another space, in the mean 2.5 cm. broad, somewhat 

 narrower inferiorly than superiorly, filled with various sized 

 secondary ossicles. 



The squamo-parietal junction and much of the fronto-parietal 

 are still membranous. 



On the right there is plainly but one parietal. This is com- 

 paratively small and somewhat irregular. In about the middle 

 of the anterior border is a V shaped defect (fontanel), corre- 

 sponding to that on the left, and filled with a moderate sized 

 secondary bone The whole fronto-parietal junction is occupied 

 by a row of such bones and the same is true of the sagittal, 

 parieto-occipital and to a less degree the squamo-parietal spaces. 

 One of the secondary bones occupies the antero-superior angle 

 of the parietal area and is of a large size, but is plainly of an 

 accessory character, formed from an accidental accessory focus 

 of ossification. Another larger bony piece occupies the astenc 

 angle. 



The skull has been somewhat deformed in preparation or dry- 

 ing and the posterior parietal region on each side is depressed, 

 showing on this account but imperfectly in the illustrations. 

 The bregma fontanel is large and partly filled with small sec- 



' No. 9754, Army Med. Museum ; gift of Dr. M. D. Spackman. 



