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JAMES ERNEST KINDRED 



each other by cartilage. They enter the brain at the posterior 

 margin of the mesial dorsal part of the arch. It is significant 

 to note here that the olfactory nerves are in the process of being 

 passively enclosed in cartilage and do not actively fenestrate it. 



Fig. 12 Cross-section through the ectethmoid region, 12-mm. Syngnathus. 

 Semidiagrammatic. Camera lucida. X 102. 



Fig. 13 Cross-section through the posterior end of the orbit, 12-mm. Syngna- 

 thus. Semidiagrammatic. Camera lucida. X 66. 



ABBREVIATIONS 



c.c, copula communis 



ct.h., ceratohyal cartilage 



ect., ectethmoid cartilage 



eth., ethmoid plate 



f. my. vent., fenestra myodomus 



trails 

 front., frontal ossification 

 hyom., hyomandibula 

 int. cart., internal carotid artery 



olf.n., olfactory nerve 

 po.pr., postorbital process 

 ps., parasphenoid ossification 

 rect.m., recti eye muscles 

 sym., symplectic cartilage 

 trab.cr., trabecula cranii 

 V, ganglion of trigeminal nerve 

 ven.j., vena jugularis 

 vo., vomer ossification 



The ethmoid plate lies ventromesial to the arch, connected 

 with it by the fibrous connective-tissue ridge already mentioned, 

 as extending along the dorsal surface of the ethmoid. In Salmo, 

 Gasterosteus, and Amiurus, the ectethmoid processes are out- 

 growths from the ethmoid cartilage. If the ectethmoid carti- 



