3o6 THE AMERICAN NATURALIST. [Vol. XXXVIII. 



mentary, compensatory bones, commonl)- known as the wormi- 

 ans. Some of these secondary centres, as a rule those in 

 locaHties where the greatest deficiencies exist, which is at the 

 fontanels, show^ often more vital strength than others, enlarge 

 to more striking dimensions and eventually, meeting and articu- 

 lating with the advancing primary parietal, seem to represent 

 and are mistaken for separated parts of this bone. There 

 is no doubt but that the great majority of the "bregma," 

 " human interparietal," and supraoccipital bones, as well as 

 many of the "separated angles of the parietal" belong to this 

 category. The difference between the compensatory bone and 

 one that arose from lack of fusion of the primary centres is 

 morphologically and particularly etiologically important. 



The third point that the case at hand illustrates very hand- 

 somely is the possibility of a formation of a vertical parietal 

 suture without any division, or totally independent of a division, 

 of the primary parietal. Had the conditions in this skull 

 advanced to a full development and particularly into adult life, 

 before which period many of the closely packed wormians fuse, 

 we should have had, unless an early synostosis obliterated the 



feature, a case very much like that of Fusari, which poscss. I am 

 inclined to think, falsely as an exami)le of vertical parietal divi- 

 sion in a human individual. 



C. I. Hapale, male, adolescent (No. 36,222, Dept. of Biol- 

 ogy, U. S. Nat. Mus.). Skull apparentlv normal, symmetrical. 

 The ordinary sutures all open. Each ^.arietal shows a plain 

 trace of a complete, vertical, now synostosed division. On the 

 left the dix ision began superiorly 9 mm. posterior to the bregma 

 and 13 mm mtctioi to the lambda, ran, slightly curving and 

 nearly parallel to the coronal suture, to the temporal ridge, then 



