3203. Porifera and Coelenterata. 22 Color Photomicrographs. 1. Sycon, marine sponge, l.s. 2. Sycon, t.s. 3. Sycon, calcareous spicules 4. Sycon, development 5. Euspongia, skeleton 6. Spongilla, winter bodies (gemmulae) 7. Hydra, w.m. 8. Hydra, t.s. 9. Hyd