Fig. 1. Entire animal of Nierstrassia fragile. X 13. 



Fig. 2. Hypodennal layer. X 800. 



Fig. 3. Reconstruction of anterior end of body. 



Fig. 4. Section through posterior end of body along Une F of fig. 5. 



Fig. 5. Reconstruction of posterior end of body. 



Fig. 6. Section through posterior end of body along line C of fig. 5. 



Fig. 7. Same along line D of fig. .5. 



Fig. 8. Section through region of brain along line A of fig. 3. 



Fig. 9. Longitudinal section through brain and anterior end of alimentary canal. X 180. 



Fig. 10. Section through posterior end of body along line E of fig. 5. 



Fig. 11. Posterior end of body, ventral view. 



