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Plate 25. 



F 



Microphotographs of thick unstained preparations showing skeletal arrangement. 



Fig. 1. Phakellia lamelligera. Section vertical to surface, and passing completely 



through lamellate wall ; in horizontal plane of sponge ; 



x 15. 



2. Auletta dendrophora. From a median longitudinal section through a "person." 



Left margin of figure represents surface of sponge; 

 right margin, surface of paragastric cavity. Along 

 latter margin appears a longitudinal skeletal fibre, 

 from which short echinating spicules project ; x 30. 



Skeletal lamella, seen from its flattened face. Long 

 projecting spicules along right and left margins of 

 figure are the spicules projecting from surfaces of 

 sponge. Lamella was dissected out and cleaned with 

 potash : x 10. 



Idem. Figure was not well reproduced, and the pro- 

 jecting (prostal) spicules are indistinct ; x 10. 



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Phakellia lamelligera. 



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