STUDIES ON THE COMPARATIVE ANATOMY OF SPONGES. 37 



DESCRIPTION OF PLATES I— IV, 



Illustrating Mr. Arthur Dendy's paper " Studies on the Com- 

 parative Anatomy of Sponges. III. — " On the Anatomy 

 of Grantia labyrinthica, Carter, and the So-called 

 Family Teichonidae." 



PLATE I. 



Figs. 1, 2, 3. — Three early stages in the post-embryonic development of 

 Grantia labyrinthica. Nat. size. 



Fig. 4. — Adult specimen of Grantia labyrinthica, growing upon a mass 

 of foreign matter. Nat. size. 



Fig. 5. — Portion of an adult specimen of Grantia labyrinthica, with a 

 bud attached to the outer surface, x 2. 



Fig. 6. — Specimen of Teichonella prolifera, showing the oscula dis- 

 tributed along the raised margin. Nat. size. 



PLATE II. 

 Skeleton of Grantia Labyeinthica. 



Figs. 7, 8, 9. — Large linear spicules (oxea) from the margin of the osculum. 

 Zeiss, D, ocular 2, camera. 



Figs. 10, 11. — Oxea from the surface of the cup. Zeiss, D, ocular 2, 

 camera. 



Fig. 12. — Large oxeote spicule from the surface of the stem. Zeiss, D, 

 ocular 2, camera. 



Figs. 13, 14, 15, 16, 17, 18. — Different forms of triradiate spicules from 

 the wall of the cup. Zeiss, D, ocular 2, camera. 



Fig. 19. — Sagittal triradiate spicule from the stem. Zeiss, D, ocular 2, 

 camera. . 



Fig. 20. — Quadriradiate spicule from the gastral cortex. Zeiss, D, ocular 

 2, camera. 



Fig. 21. — Arrangement of quadriradiate spicules around the exhalant canal 

 of a young flagellated chamber. 



Fig. 22. — Arrangement of the skeleton as seen in vertical longitudinal 

 section of a chamber from gastral to dermal surface. 



PLATE III. 



Anatomy of Gkantia Labyrinthica. 



Fig. 23. — A single flagellated chamber and its exhalant canal, in part laid 

 open by longitudinal section, ex. c. Exhalant canal, di. Diaphragm, pr. 



