588 



LOCK 



Fig. 36. Somewhat older embryo differing from the preceding mainly in show- 

 ing the rudiments of the seventh, eighth, ninth, and tenth nerves. Note the 

 lens and choroid fissure in the eye vesicle. 



Fig. 37. Slightly older than the preceding. The line of neural segments are 

 undergoing some changes whereby the concavity on the lower margin is made to 

 correspond with a crest on the upper margin. In embryos of about the age repre- 

 sented in Fig. 36 or a very little older the epiphysial outgrowth arises from the 

 roof of the thalamencephalon. 



