38 



LECTURE II. 



the two parietal bones — the stdura coronalis,* Tlie two pai'ietal 

 bones are separated by a longitudinal suture {the sutura sagit- 

 taUs).-f In tlie earliest stages of existence this suture is con- 

 tinued to the root of the nose and thus divides the frontal bone 

 into two symmetrical halves, but in normal skulls the aperture 

 is closed before birth ; in some broad heads the frontal suture 

 remains during life. The sagittal suture terminates in the oc- 

 ciput, where it touches a triangular suture which separates the 

 occipital from the parietal bones, and is called the lambdoid 

 suture. 



The cranial bones are developed at the expense of a cartila- 



Fig. 5. Outline of an adult skull with persistent frontal sutui-e, top view, 

 after Welcker. The positions of the two fontanelles are marked by dotted 

 lines, as well as the outlines of the bones as they are developed in the new- 

 born child. 



a. Frontal suture, b. Coronal suture, c. Lambdoid suture, d. Sagittal 

 sutui-e. e. Anterior Fontanelle. /. Posterior fontaneUe. g. Frontal protu- 

 berances, i. Occipital protuberance (not visible), k. Frontal bone. I. Pa- 

 rietal bone. m. Occipital bone. 



* " Pronto-parietal" suture. — Editor, f " Interparietal" suture. — Editor. 



