746 



DEVELOPMEXT OF THE NERVOUS SYSTEM. 



b. Ill the Trnnh. 



The bodies, arches, and processes of the vertebraa. 

 The ribs and sternum. 



c. In the Limbs. 



The scapula and coracoid. The clavicle in part, and all the other bones of the 

 Tipper limbs (excepting sesamoid). 



The ilium, ischium, and pubis, and all the other bones of the lower limbs, 

 including the patella, but excepting sesamoid of toe. 



2. BoJies arittiiig from Fihvcms Memirane : — 



a. In the Head. 



Pai-t of the squama occipitis. 



The frontal. 



The parietal. 



The squamo-zygomatic and tympanic of the temporal. 



The nasal and lachrjTual. 



The maxillaries and i3re-maxillaries. 



The vomer and comua sphenoidalia. 



The inferior or maxillo-turbinal. 



The malar or jugal. 



The inferior maxillary or mandibular. 



i. Ill the Trunh. None. 



c. In the Limbs. 



The clavicle in part. 



(The marsupial bone of animals.) 



The smaller sesamoid bones of tendons. 



DEVELOPiUENT OF THE NERVOUS SYSTEM. 



The Cerebro-spinal Centre. — From what has been previously 

 stated it will have been seen that the rudiment of the cerebro-spinal 



Fig. 514. 



Fig. 545. 



Fig. 544. — Embryo of the Doo seen from above, ■with a portion of the 

 Blastodekm attached (from Bischofi"). 



Tlie medullary canal, not yet closed, shows at the cephalic extremity a partial 

 division into the three jirimary cerebral vesicles ; and at the posterior extremity a 

 rhoniboidal enlargement. Six proto-vertebral divisions are visible ; so, the upper division 

 of the blastoderm, sp, the lower division. 



