358 THE SPONGIDA OR PORIFERA. 



EXPLANATION OF PLATES XIV., XV., XVI. 



Plate XIV. 

 Fig. 1. — Halichondria panicea, the Crumb-of-Bread Sponge, taken off 



a piece of rock ; a, a, oscula, or foecal orifices. 

 ,, 2. — Halichondria pcmicea, the Crainb-of-Bread Sponge, growing 



on and around sea- weed (Fiicus) h ; 6 1, channel in sponge 



once filled by seaweed ; a, a, oscula. 

 ,,3. — Halichrondia e7icrustans growing on and around sea- weed 



(Chrondrus), h, h ; a, a, oscula. 

 ,, 4. — Sycandra compressa, the Sack Sponge ; a, oscula. 

 ,, 5. — Sycandra ciliata, the Crowned Sponge ; a, oscula. 



Plate XV. 



Fig. 1. — Sycandra Ciliata, the Crowned Sponge. Part of longitudinal 

 section , showing collared flagellate cells lining radial tubes, 

 and a few spicules, as seen with a l/12th inch objective. 



,, 2, — Isolated collared flagellate cells, greatly magnified, and drawn 

 from the same slide as above, a, a, collar ; h, h, flagellum ; 

 c, neucleus, containing neucleolus ; d, d, contractile vesicles ; 

 e, e, granular protoplasm. 



Plate XVI. 



Fig. 1. — Halisarca lohidaris, diagram of vertical section, a, a, Pores 

 or apertures of afferent canals ; b, h, ampullaceous sacs, 

 monad chambers, or ciliated chambers ; c, efferent canal 

 leading to osculum. 



,, 2. — Sycandra co7npressa, diagram of transverse section of Sponge, 

 showing one entire radial tube or ciliated chamber, a, Pore 

 through which water enters ; b, efferent channel opening into 

 central cloacal chamber ; c, flagellate collared cells lining 

 radial tube or chamber ; d, external defensive spicula ; e, 

 internal triradiate spicula. 



,, 3. — Diagrams of flagellate collared cells from Sycandra comiwessu, 

 in various stages of metamorphosis, a, cell, with collar, 

 flagellum, neucleus {j) and neucleolus, and contractile vesicles 

 {k) ; 6, c, cells in different stages of metamorphosis ; c?, e, 

 groups of cells in different stages of change, collars and 

 flagella being retracted in some, extensions of sarcode into 

 processes, or pseudopodia, occurring in others, and granular 

 food being ingested Q) in some ; /, g, h, i, cells variously 

 metamorphosed and amoebiform. 



4. — Detached ciliated cell from Grantia (Sycandra) compressa, as 

 described by Bowerbank. 



5. — Diagram of a flagellate collared independent monad, Monoskia 

 gracilis. a, collar ; b, flagellum ; c, c, ingested food gran- 

 ules ; d, neucleus, with neucleolus ; e, e, contractile vesicles ; 

 /, particles of food. 



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