STUDIES ON THE COMPARATIVE ANATOMY OF SPONGES. 357 
PLATE XXXI. 
Stelospongus flabelliformis. 
Pig. 4. — A small portion of the ectosome, removed from the surface and 
examined from above as a transparent object after staining with borax carmine, 
showing the pores (/>.) arranged in pore-areas (p. a.); the cystenchymatous 
tissue (cy.) lying beneath is seen through the transparent epidermis. Drawn 
under Zeiss’s C, ocular 2. 
Fig. 5. — A solid section, showing the oscular tube ( o . t.) partially dissected 
out, with the openings of its various branches ; an osculum (o.) and two 
embryos ( e .). On the right of the oscular tube are two of the embryo cap- 
sules ( e . c .) from which the embryos have been removed, x 2. 
Fig. 6. — Portion of a section through the choanosome, showing the rela- 
tions of the ultimate inhalant lacunae (i. e.), the flagellated chambers (/. c.) 
and the ultimate exhalant lacunae ( e . L). Drawn under Zeiss’s F, ocular 2. 
Fig. 7. — Section through a single flagellated chamber, showing Sollas’s 
membrane (r. m .) as it very often appears in ordinary preparations. Drawn 
under Zeiss’s F, ocular 2. 
Fig. 8. — Small portion of an actual vertical section through the wall of a 
flagellated chamber, showing three collared cells connected together at the 
margins of the collars by a delicate membrane, seen iu section ( r . m.), Sollas’s 
membrane. The granular bodies (y.) on the collars ( c .) may possibly represent 
the last remnants of shrivelled-up flagella. Drawn under Zeiss’s F, 
ocular 2. 
PLATE XXXII. 
Stelospongus flabelliformis. 
Fig. 9.— Diagram of a portion of the wall of a flagellated chamber, showing 
the various parts of the collared cells and their relations to the reticulate 
membraue (Sollas’s membrane, r. m.) which connects together the margins of 
the collars. 
Fig. 10. — Diagram of a section through a flagellated chamber, passing 
through the inhalant (i. o .) and exhalant (<?. o.) openings, showing the arrange- 
ment of the collared cells ( c . c.) and the relations of the inhalant (*. 1.) and 
exhalant ( e . 1.) lacunae, and inhalant (i. c. c.) and exhalant {e. c. c.) cameral 
canaliculi. 
Fig. 11. — A group of spongoblasts ( spb .), showing their form and relations 
to the skeleton fibre (/.). Drawn under Zeiss’s F, ocular 2. 
Fig. 12. — Portion of a plexus of stellate mesodermal cells from around a 
grain of sand in the ectosome. Drawn under Zeiss’s F, ocular 2. 
Fig. 13. — Cystenchyme from the ectosome, from a section stained with 
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