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rOPULAR SCIENCE REVIEW. 
Fig. 10. A monad of the above dividing by longitudinal fission. 
„ 11. A monad of the same species, with the collar and flagellum with- 
drawn, emitting pseudopodic processes. 
„ 12. An encysted monad of the same species with the body broken up 
into spores. 
„ 13. An adult colony of Codosiga grossulariata , S. K. 
„ 14. An adult colony of Codosiga pynformis, S. K. 
,, 15. Single individual of Monosiga brevipes, S. K. 
„ 16. Monosiga globularis, S. K., showing at a and b free-swimming and 
attached larval forms. 
„ 17. Adult colony of Codosiga candelabrum , S. K. 
„ 18. Single individual of Monosiga gracilis , S. K. 
,, 19. Body of the same still further enlarged and diagrammatically 
illustrating the feeding process described at p. 117. The arrows 
indicate the direction of the current caused by the rotatory motion 
of the flagellum and the course taken by the food particles on 
striking against and adhering to the collar, jl. Flagellum, c. 
Collar, n. Nucleus. /. Food-particles, cv. Contractile vesicles. 
„ 20. Free-floating colony of Astrosiga disjuncta , S. K. 
„ 21. Four monads of Monosiga consociatum, S. K. : at a an individual 
in a quiescent or encysted state. 
„ 22. An individual of the same species assuming an amoeboid form and 
exhibiting extensive internal vacuolation. 
„ 23. Adult free-floating colony of eight monads of Desmarella monili- 
formis, S. K. 
„ 24. Colony of two individuals of Codosiga furcata, S. K. 
„ 25. Animalcule figured by Stein as probably the young of Opercularia 
nutans, but probably identical with the above species. 
„ 26. Abnormal colony-form of Codosiga cymosa, S. K. 
„ 27. Free-swimming multiple-fission gemmule of a calcareous sponge* 
Sycon ciliatum, in diagrammatic longitudinal section. 
„ 28. A more advanced stage of the above, in which the separate flagel- 
late cells have acquired the characteristic collars of the adult 
sponge-monads. 
„ 29. An adult sponge-monad of Grantia compressa in its normally ex- 
panded state, n. Nucleus, cv. Contractile vesicle. 
„ 30. A collar-bearing monad from the same sponge emitting pseudopodic 
processes from its posterior extremity. 
„ 31 . A monad from the same sponge with the collar and flagellum with- 
drawn assuming an Acineta-fa&SQ. 
„ 82. Initial or mono-flagellate larval condition of a siliceous sponge, 
Halichondria. 
„ 33. Sporocysts of a siliceous sponge, Halichondria. 
„ 34. Portion of syncytium of a calcareous sponge, Leucosolenia botryoides, 
having imbedded in its substance a sporocyst containing spores, 
and also free spores recently liberated from a similar cyst. 
„ 35. Section through a monad-chamber or 1 ampullaceous sac ’ with its 
contained collar-bearing monads, and portion of the syncytium of a 
siliceous sponge, a. Ampullaceous sac. b. Amoeboid particles or 
cytoblasts. 
