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SYDNEY EVANS JOHNSON 





Fig. 32 Surface view of a 13 mm. embryo. Squalus acanthias. From a 

 sketch by Otto Swezey. X 10. 



Fig. 33 Surface view of a 15 mm. specimen. Note the epidermal pocket at 

 the growing end of the hiteral cord. Scjualus acanthias. From a sketch by 

 Otto Swezey. X 10. 



Fig. 34 Lateral dissection of the medulhi of a 15 mm. embryo of Squalus 

 showing roots and ganglia of the lateralis and vagus nerves. X 20. 



Fig. 35 Horizontal section through the posterior part of lateralis ganglion, 

 showing fibers from the ganglion cells extending into the thickened ectoderm 

 of the lateral cord. Squalus, 15 mm. specimen. X 492. 



Fig. 36 Horizontal section, from the same specimen as figure 35, but taken 

 at the growing end of the lateral sensory cord. Shows the epidermal fold over 

 the greatly enlarged growing end of the sensory cord; nerve fibers extend among 

 the cells of the latter. Squalus, 15 mm. X 492. 



