74 THE TOXER LECTURES. 



were slightly curved. They were undoubtedly developed in the 

 direction of the vertical fibres of the temporal muscle.^ 



The pneumatic process of the occijoital bone was met with in 

 six' instances. In six of these the process was on the left side. 



The paroccipital process may be bent inward and flattened,'' and 

 in one instance was found to articulate on the left side with the 

 atlas.* 



Rer/ions of great density of bone structure. — The disposition for 

 some parts of the cranium to show dense ivory-like thickenings is 

 very noticeable. The causes which induce the vascular cancellous 

 tissue to assume greater density with diminution of blood-vessel 

 supply would be interesting to trace. Four localities are named 

 for the occurrence of this change — 1st, the petrous portion of the 

 temporal bone; 2d, the inner or vitreous plate of the bones entering 

 into the composition of the vertex;^ 3d, the margins of the jugular 

 foramen, notably the anterior; 4th, occasionally in the interior 

 of sinuses, as seen in the maxillary and ethmoid sinuses. 



The disposition to ivory-like density is often morbid (this prob- 

 ably includes the third and fourth groups as given above), and 

 may even be present in the vitreous plate of the vertex. Scarcely 

 a cranium can be found in our dissecting-rooms in which solid 

 nodules are not found in some part of the interior of the cal- 

 varium, especially at the frontal jwrtion on either side of the me- 

 topic line. Many individuals exhibit dense, white, low eminences 

 of the general internal surface at the region of the bregma. They 

 are lozenge-shaped and measure four to six centimetres in diameter. 



^ See No. 1271, ZSorth Americivn Indian; No. 742, Mandan ; No. 963, 

 negro. 



2 No. 1229, Upsarooka; 20, Bengalee; 78, 85, Menominee; 204, Che- 

 nook; 707, Seminole. 



^ See skull of Alaskan in museum of Princeton College, N. J. 



* No. 706, German. 



^This is seen to be the case to a remarkable degree in the skull of an 

 Esquimau.x (No. 1554) in the Army Medical ^luseum. 



