38 



SYDNEY EVANS JOHNSON 



CI.Gn. 



m.Aud.Qnflt Z. Latn. 

 A 



Sp Gn. X. Rt. 



Mrdl. 



UtJ. UtGn. z. 30 



La.tU 



„?s?- 



A5» 



Fig. 29 Surface view of an 11 mm. embryo showing the various structures con- 

 cerned in the formation of the sensory canal system. Squalus. From a sketch 

 by Otto Swezey. X 16. 



Fig. 30 Lateral dissection of the medulla spinalis showing early separation 

 of lateralis root and ganglia from the vagus complex. Squalus, 11 mm. X 20. 



Fig. 31 Transverse section of the thickened ectodermal cord at position indi- 

 cated by line A-B in figure 29. X 466. 



