
PERFORATED AND DISTORTED CRANIUM. AT 
excessive thinning of the bone, are symmetrically placed, and not always in 
the same position. They may be present along with thinnings of the bones, 
and along with the clefts representing parietal foramina. They do not occur 
in the exact situation of the parietal foramen. When the bone is thinner 
than usual, it has a cribriform character. 
Both thinnings and perforations in the foetal bones look exactly as if, 
owing to inequality of growth in the cranium and cerebrum, pressure had 
been exerted upon the ossifying parietal bones by the subjacent cerebral con- 
volutions. But the usual parietal perforations occur in the situation of the 
normal parietal foramina. It has been shown that the existence of the usual 
vessel or vessels in the ordinary course of events retards the bone formation. 

Fic 11.—Parieran Bone or A Ninze-Montu Fetus 
PERFORATED AND THINNED. 
It is conceivable that in certain cases, it may be along with larger or more 
numerous vessels, the same inequality of growth and consequent pressure of 
the cerebral convolutions may keep open and enlarge this embryonic cleft, 
and so give rise to the large perforations present in some few cases. In one 
of our cases there is coalescence of the perforations across the middle line ; 
and in another a suture connects them together. The idea of such a cause 
being responsible is supported by the fact that in several of the examples 
recorded the cranium has a microcephalic character, or there is partial or 
complete obliteration of the cranial sutures. 
One is inclined, therefore, to causally associate the general condition of 
the cranium described, arrest of development of the base, closure of sutures, 
and microcephalic character, with the existence of these enormous perfora- 
tions of the parietal bones. 
Bibliography. 
(1) CUNNINGHAM and TELFORD SMITH, Scientific Transactions of the 
Royal Dublin Society, vol. v., series 2 (viii.), 1895. 
