1 6 SURGICAL APPLIED ANATOMY. [Chap.n 



if occupied by parchment, or, as some suggest, by 

 cartridge p-vper. The thinning is mainly at the 

 expense of the inner table and diploe. The pits are 

 situated in early formed convolution impressions. It 

 is, on the other hand, about the site of the anterior 

 fontanelle that certain osseous deposits are met with 

 on the surface of the skull in some cases of hereditary 

 syphilis (Parrot). These deposits appear as rounded 

 elevations of porous bone situated upon the frontal 

 and parietal bones, where they meet in the middle 

 line. These bosses are separated by a crucial depres- 

 sion represented by the frontal and sagittal sutures on 

 the one hand, and the coronal suture on the other. 

 They have been termed " natiform " elevations by M. 

 Parrot, from their supposed resemblance, when viewed 

 collectively, to the nates. To the English mind they 

 would rather suggest the outlines of a " hot-cross 

 bun." 



It is necessary to refer to the development ol 

 the skull in order to render intelligible certain con- 

 ditions (for the most part those of congenital mal- 

 formation) that are not unfrequently met with. 

 Speaking generally, it may be said that the base of 

 the skull is developed in cartilage, and the vault in 

 membrane. The parts actually formed in membrane 

 are represented in the completed skull by the frontal 

 and parietal bones, the squamo-zygomatic part of the 

 temporal bone, and the greater part of the expanded 

 portion of the occipital bone. The distinction between 

 these two parts of the skull is often rendered very 

 marked by disease. Thus there are, in the museum 

 of the Royal College of Surgeons, the skulls of some 

 young lions that were born in a menagerie, and that, 

 in consequence of mal-nutrition, developed certain 

 changes in their bones. A great part of each of 

 these skulls shows considerable thickening, the bone 

 being converted into a porous structure ; and it is 



