Plate 12. 



Fig. 1. Thenea echinata. Upper surface ; from a photograph ; \. 



" 2. " " From a radial section ; upper surface of sponge and adjoin- 

 ing parenchyma; x 20. 



" 3. " " Spirasters ; x 600. 



4. " " Protriaene ; x 30. 



" 5. " " Dichotriaene, modified toward protriaene ; x 30. 



" 6. " " Spicule from root ; clavate at one end ; x 100. 



" 7. " " Cladome of dichotriaene ; x 30. 



" 8. " " Somal anatriaene ; x 100. 



" 9. " " From a photograph ; from the side ; \. 



" 10. Thenea lamelUformis. Anatriaene, somal ; x 150. 



" 11. " " Anatriaene, radical ; x 150. 



" 12. " " Anatriaene, somal ; x 40. 



" 13. " " Upper surface ; from a photograph; \. 



