38 ARTHUR DENDT. 



Prosopyle. fl. c. Cavity of flagellated chamber, em. Embryo, em. c. Embryo- 

 containing cavity (the embryo has already escaped in this case). The collared 

 cells are coloured red, and the embryos brown. Zeiss, J), ocular 2. 



Fig. 24. — Exhalant opening of a flagellated chamber, with its membranous 

 diaphragm {di.). mus. Muscle-cells. The spicules are coloured blue, and the 

 collared cells (which lie somewhat below the level of the diaphragm) red. 

 Zeiss, F, ocular 2. 



Fig. 25. — Part of a section vertical to the margin and to the two surfaces 

 of the wall of the cup. em. Embryo, o. sp. Spicules of the oscular fringe. 

 p. Inhalant pore. p. a. Pore-area. in. c. Inhalant canal. g. s. Gastral 

 skeleton, d. s. Dermal skeleton, t. s. Tubar skeleton. Other lettering and 

 colouring as before. Zeiss, A, ocular 3, 



Fig. 26. — Gastral portion of a thin section similar to the last, but more 

 highly magnified. ffl. c. Gland-cells lying beneath the gastral epithelium. 

 st. c. Stellate cell. Other lettering and colouring as before. Zeiss, F, 

 ocular 2. 



Fig, 27. — Vertical section through the young specimen represented in Fig. 

 1. gas. c. Gastral cavity, vies. Growth of mesodermal tissue filled with 

 spicules, to form the stalk. Flagellated chambers red, spicules blue. 



PLATE IV. 



Anatomy of Grantia Labyrinthica. 



Fig. 28. — Portion of a section taken parallel to the surface of the sponge- 

 wall, and somewhat nearer to the dermal than to the gastral surface. It will 

 be noticed that the inhalant canals are still of large size. s. sp. Sections of 

 the shafts of the triradiate spicules of the tubar skeleton, x. Peculiarly 

 modified flagellated chamber. Other lettering and colouring as before. Zeiss, 

 D, ocular 2. 



Fig. 29. — Portion of a section similar to the last, but taken near the gastral 

 surface, showing the diminution in diameter of the inhalant canals, &c. 

 Lettering and colouring as before. Zeiss, D, ocular 2. 



Fig. 30. — Portion of the dermal surface sliced off, showing the pores 

 arranged in pore-areas. Some of the spicules are omitted. Lettering and 

 colouring as before. Zeiss, A, ocular 2. 



Fig. 31. — A single pore more highly magnified, showing the nerve-cells 

 («. c.) around its margin. Zeiss, F, ocular 2. 



Fig. 32. — A group of collared cells (with retracted collars and flagella), 

 seen from above or below. «. Nucleus. Zeiss, F, ocular 3. 



Fig. 33. — A row of four collared cells (with retracted collars and flagella), 

 seen from the side. n. Nucleus, s. m. Sollas's membrane shrunk down 

 upon the apices of the cells. Zeiss, F, ocular 3. 



Fig. 34. — A single gland-cell {gl. c.) connected by four processes with the 



