PLATE II. 



Class PORIFERA. 



A HOLLOW CALCAREOUS SPONGE (Grantia compressa). 



FIG. 1. Two SPECIMENS, ONE WITH A SINGLE EXHALANT OPENING OR OSCULUM, 

 THE OTHER WITH TWO SUCH OPENINGS. X 1. 



FIG. 2. SHOWING PART OF THE BODY WALL RAISED TO EXPOSE THE INTERNAL 

 CAVITY, x 1. 



FIG. 3. PART OF THE EXTERNAL SURFACE, SHOWING THE TRI-RADIATE SPICULES 

 ARRANGED AROUND THE INHALANT OPENINGS. X 50. 



FIG. 4. PART OF THE SAME, x 600. 



FIG. 5. LONGITUDINAL SECTION OF ONE OF THE INCURRENT CANALS (SEEN ON 

 MAKING A TRANSVERSE SECTION OF THE SPONGE). (From nature, 

 and partly after Bowerbank.) x 400. 



FIG. 6. FLAGELLATE COLLARED MONADS, x 1200. 



FIG. 7. ONE OF THE MONADS, x 1800. 



n. nucleus : c. collar : /. flagellum. 



