THE LARVA OF TIPULA MAXIMA. 



131 



Fig. 13. Portion of section across the posterior region of the body, showing the tracheal tubules 

 radiating from the bundles and becoming attached to the body-wall. 

 11. Portion of the above, more highly magnified. 

 15. Portion of a horizontal longitudinal section of the: heart. 

 16'. Portion of the above at the ostium, more highly magnified. 



17. Blood-cells. 



18. Transverse sections across the blood-gills. 



19. Dissection of a larva from the dorsal side, showing the distribution of the dorsal tracheal tubes. 



20. Sections across the wall of the heart. 



21. Median radial section across the spiracle of the aquatic type. 



22. Tangential section across the marginal region of the same. 



