SEPTUM, HIPPOCAMPUS, PALLIAL COMMISSURES 



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Fig. 5 Chelydra serpentina, 10 mm. embryo, median sagittal section. Magn. 

 52 diam. In the 6, 9 and 10 mm. stages the lamina supraneuroporica grows in 

 thickness. The point of transition to the tela is the margo posterior pallii. The 

 fibers of the anterior commissure are evident in this stage. 



Fig. 6 Chelydra serpentina, median sagittal section of the brain of a speci- 

 men having a carapace 8 mm. in length. Magn. 17 diam. The thickening of the 

 lamina supraneuroporica now begins to encroach upon the recessus neuroporicus, 

 which is nearly obliterated in the adult. 



