26 



Normentafeln zur Entwicklungsgeschichte der Wirbeltiere. 



Stage 



Series 



233 Sag. 



48 a 



49 



234 Trans. 



236 Sag. 



237 Front. 



Lengtli 



Age 



Body Form 



36 mm 



38 mm 



39 mm 



110 days 



126 days 



Has practically 

 reached adult con- 

 dition except in color 

 ation. Same bands 

 prominent as in pre- 

 ceding stage. Lateral 

 band mottled. 



Somites 



Notochord 



Anterior end at level 

 of hypophysis, some- 



times beyond it. 



Intervertebral carti- 



lages thicker. Bodies 



of vertebrae more 



constricted. Layer of 



bone around cord 



thicker. 



Nervous System 



Ossification very 



complete in neural 



spines and basal pro- 



cesses in ribs, and in 



haemal arches; be 



ginning in haemal 



spines. 



Eye 



Ear 



Eye nearly spherical, 

 slightly flattened later- 

 ally. Retina as in 



26 mm excepting 



ganglionic layer is 

 one cell thick. Othei 

 layers together with 

 external and internal 



limiting membrane 

 sharply defined. Iris, 

 choroid, Cornea and 

 sclerotic as in 26 mm. 



Lens capsule cells 



much more elongated 



tangentially. 



1 



I 



i 



