Fig. 79 Pig embryo, 28 mm. The lamina supraneuroporica is raised to a 

 more vertical position by the growth of the hemisphere and the thalamus is rela- 

 tively crowded. There is still no commissure visible in the lamina supraneuro- 

 porica but it is somewhat thicker than in the 23 mm. stage. 



Fig. 80 Pig embryo, 40 mm. The lamina supraneuroporica is still more 

 elevated and the paraphysal arch is crowded into a deep narrow sac, in front of 

 the developing choroid plexus. Now the anterior pallial commissure is evident 

 as a fibrous mass occupying the lamina supraneuroporica. There is up to this 

 time no secondary fusion nor extensive thickening in the region of the commis- 

 sures. 



471 



