Plate IV. 



Fig. 42. Duodeuum. Tadpole No. V, Fig. 2. Cross-section. X 750. 



Fig. 43. Duodenum. Tadpole No. VI, Fig. 2. Detail of Fig. 20. Cross- 

 section. X 750. 



Fig. 44. Cross-section of the posterior part of the small intestine of tadpole, 

 No. VII, Fig. 2. Detail of Fig. 16. X 750. 



Fig. 45. Duodenum. Tadpole No. VII, Fig. 2. Detail of Fig. 17. Cross- 

 section. X 612. 



