406 WILSON. 
EXPLANATION OF PLATE XXV. 
(Fig. 5 original — the other figures borrowed to illustrate the section “Re- 
marks on the Morphology of Sponges.”’) 
Fic. 1. Anamixilla torresi. Trans. section, from Polejaeff, Challenger Report 
on Calcarea, Pl. IV, Fig. 2a. 
Fic. 2. Leucilla connexiva. Trans. section, from Polejaeff, Pl. VI, Fig. 1a. 
Fic. 3. Leucilla uter. Trans. section, from Polejaeff, Pl. VI, Fig. 2a. 
Fic. 4. Leuconia multiformis. Trans. section, from Polejaeff, Pl. VI, Fig. 3a. 
Fic. 5. Diagrammatic section of an hypothetical silicious sponge. 
Fic. 6. Leucandra caminus. From Vosmaer’s Spongien, Taf. I, Fig. 18, after 
Haeckel. 
Fic. 7. Plakina monolopha. Vertical section, from Schulze. Zeit. fiir Wiss. 
Zool., 34. Bd., Taf. XX, Fig. 4. 
Fic. 8. Young Plakina monolopha, just attached. Vertical section, from 
Schulze, l. c. 
Fic. 9. Plakina dilopha. Vertical section, from Schulze, ]. c. Taf. XX, 
Bioeur. 
. Fic. 10. Plakina trilopha. Vertical section, from Schulze, 1. c. Taf. XXI, 
Hig. 212) 
Fic. 11. Rhagon stage of Oscarella lobularis, after Heider, from Korschelt 
und Heider’s Lehrbuch, p. 6. 
REFERENCE LETTERS TO THIS PLATE. 
af. ¢. Afferent canal. mes. Mesoderm. 
Gop Chamber pore. Os. Osculum. 
ec. Ectoderm. Par. cav. Paragastric cavity. 
en. Entoderm. r. W. “ Ringwall.” 
ec. Efferent canal. MEE Radial tube. 
kG. Flagellated chamber. Grips Surface pore. 
In. can. Intercanal. 
