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Fig. 1. Tylodesma vestibularis 



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a 



c< 



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3. 



5. 



Plate 19. 



From a photograph. Sponge viewed from the side ; 

 whitish conglomerate below. Vestibular spaces ap- 

 pear as darker areas. The one best brought out in 

 the figure is well to the left, and has indented mar- 

 gins. The small darker area at extreme left of this 

 space is an osculum ; x}. 



1 



2. Phakellia lamelligera. Spicules; x 70. 



" " From a photograph. Sponge seen obliquely from the 



side ; x T 7 <y. 



4. Auletta dendro-phora. Inner face of sponge wall, lining paragastric cavity. 



Apertures of radiating canals appear; I. b., longitu- 



dinal skeletal bundles ; x 100. 



Surface 



a 



From a transverse section through a "person." 



of sponge above. A radiating canal opens into a 

 subdermal cavity, s. c. Part of the wall of the latter 

 is seen in perspective. Wall of another cavity in 

 lower left corner seen in perspective. On each side 

 of the radiating canal, section strikes a radiating 

 bundle of spicules (styles) ; x 100. 



Microscleres ; a, anisochela in lateral view ; b, bipocillus 

 from concave side ; c, bipocillus, apical view of larger 

 end; d, bipocillus from convex side; e, bipocillus in 

 lateral view ; x 1000. 



7. Auletta dendrophora. From a photograph ; sponge seen somewhat obliquely 



from the side ; x j. 



6. Iophon indentatus. 





