THE LIMBS 



21 



Fig. 26. — ^Lateral View of a Human Embryo 18 mm. Long, Showing the Development of 

 THE Extremities. M, mandibular arch. 



Fig. 27. — Diagram to Show the Derivatives of the Branchial Clefts, le, lie, Ille, 

 IVe, Ve, external branchial grooves, li, Hi, lilt, l\i, Yi, internal branchial grooves. Tons.', 

 palatine tonsil. Ep III, Ep IV, epithelial bodies. Ub, ultimobranchial bod3^ Th., thj'reoid 

 gland. D.th. gl., ductus thyreoglossus. (Modified rom Keibel and Mall.) 



Thymus 



