PLATE I. (FRONTISPIECE.) 



SPONGE. 



Page 



Fig. 1. Circulation and gemmules of the Sponge 

 (Spongia papillaris). a. Section of the 

 living sponge. b. Gemmule magnified, show- 

 ing the cilia 30 



Fig. 2. NONIONINA GERMANICA. a. The same after 



the dissolution of its shell by means of acid . 39 



Fig. 3. NOCTILUCA 49 



Fig. 4. MEDUSA CHRTSAOEA (Dalyell) 78 



Fig. 5. HYDRA TUBA 68 



Fig. 6. TURRIS NEGLECTA 62 



Fig. 7. SARSIA GEMMIFERA 65 



Fig. 8. STOMOBRACHIUM OCTOCOSTATUM. Seen from 



below 64 



Fig. 9. STOMOBRACHIUM OCTOCOSTATIJM. Lateral view. 64 



Fig. 10. CYDIPPE POMIFORMIS. a. Newly extruded egg. 

 b, c, d, e. Progressive development of the 

 embryo 97 



Fig. 11. CTANEA CHRYSAORA. Upper surface 57 



Fig. 12. CYANEA CHRYSAORA. Seen from below .... 57 



