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ARTHUR DENDY. 
borax carmine and mounted in Canada balsam. Drawn under Zeiss F, 
ocular 2. 
Fig. 14. — A single cystenchyme cell from the ectosome, showing the 
nucleus ( n .) suspended in a network of protoplasmic threads. From a pre- 
paration mounted in glycerine without embedding. Drawn under Zeiss’s F, 
ocular 2. 
Fig. 15. — Portion of the fibrous layer of an embryo capsule. The right 
hand side of the figure corresponds to the inner portion of the layer, next to 
the lining epithelium. Drawn under Zeiss’s F, ocular 2. 
PLATE XXXIII. 
Stelospongus flabelliformis. 
Fig. 16. — Group of large nutrient epithelial cells, from the lining epithelium 
of an embryo capsule. Drawn under Zeiss’s D, ocular 2. 
Fig. 17. — Vertical section of one of the large nutrient epithelial cells from 
the lining epithelium of an embryo capsule. Drawn under Zeiss’s F; ocular 2. 
Fig. 18. — Portion of the surface of a large embryo, as seen with a hand 
lens, showing the shallow pits on the surface (pi.), aud on the left of the 
figure the nutrient epithelium from the embryo capsule [nut. e.) still adherent. 
Fig. 19. — Portion of a radial section of an embryo, showing the ectodermal 
layer of cells ( e . 1. c.), and the large amoeboid cells [a. c.) embedded in the 
inner jelly-like mass. (The transparent gelatinous matrix is not represented.) 
Drawn under Zeiss’s C, ocular 2. 
Fig. 20. — Outer portion of a section similar to that represented in Fig. 19, 
more highly magnified, with the remains of a nutrient epithelial cell [nut. c.) 
still visible. The section corresponds to a transverse section through a single 
one of the shallow pits represented in Fig. 18. 
Fig. 21. — Vertical section through one of the large nutrient epithelial cells 
[nut. c.), with the ectodermal cells of the embryo [c. e. 1.) attached to its inner 
surface by means of slender prolongations of their necks. Drawn under 
Zeiss’3 F, ocular 2. 
Fig. 22. — Small portion of a section through an embryo, showing how the 
ectodermal cells [c. e. 1.) become amoeboid [a. c.), and migrate inwards. Drawn 
under Zeiss’s F, ocular 2. 
Fig. 23. — Portion of a section through the interior only of the most 
advanced embryo, showing how the large amoeboid cells [a. c.) break up into a 
great many minute spherical cells, which arrange themselves around a central 
cavity and form the young flagellated chambers [/. c.). Drawn under Zeiss’s 
F, ocular 2. 
