EXPLANATION OF PLATE XXXIX. 

 FIG. 



i, 2. EPISTYLIS BRANCHIOPYLA, Perty, vol. ii. p. 705.!, Fragment of colony-stock, 

 X 200 ; 2, encysted zooid, x 200 (Stein). 



3. EPISTYLIS ARTICULATA, From., vol. ii. p. 707, x 200 (De Fromentel). 



4. EPISTYLIS LEUCOA, Ehr., vol. ii. p. 704, x 100 (Ehrenberg). 



5. EPISTYLIS BALANORUM, Meresch., vol. ii. p. 709. Isolated zooid, x 240 (Meresch- 



kowsky). 



6. EPISTYLIS GALEA, Ehr., vol. ii. p. 701. Terminal branch with two zooids, x 120 



(Ehrenberg). 



7, 8. EPISTYLIS TUBIFICIS, D'Udk., vol. ii. p. 707. 7, Adult colony-stock, x 120 ; 

 8, zooid with irregularly developed posterior prolongations (D'Udekem). 



9-1,1. OPERCULARIA HOSPES, From., vol. ii. p. 714. 9, Expanded, 10 and n, con- 

 tracted zooids, x 200 (De Fromentel). 



12-15. EPISTYLIS PLICATILIS, Ehr., vol. ii. p. 701. 12, Three zooids containing ciliated 

 embryos derived through the disrupture of the endoplast, x 200 ; at a a a, 

 spout-like apertures whence similar embryos have made their escape ; 13, 

 fragment of endoplast enclosing three embryos ; 14 and 15, isolated embryos 

 more highly magnified (Claparede & Lachmann). 



16. OPERCULARIA MICROSTOMA, Stein, vol. ii. p. 713, x 200 (Stein). 



17. OPERCULARIA STENOSTOMA, Stein, vol. ii. p. 712, x 200 (D'Udekem). 



18. EPISTYLIS INVAGINATA, C. & L., vol. ii. p. 706. Isolated zooid, x 200 (Clap. & 



Lach.) 



19. EPISTYLIS CRASSICOLLIS, Stein, vol. ii. p. 705. Fragment of branch with two 



zooids, x 200 (Stein). 



20. OPERCULARIA LICHTENSTEINII, Stein, vol. ii. p. 712, x 200 (Stein). 



21. OPERCULARIA CYLINDRATA, Wrz., vol. ii. p. 713. Terminal branchlet with two 



zooids, x 300 (Wrzesniowski). 



22, 23. OPERCULARIA NUTANS, Ehr. sp., vol. ii. p. 710. 22, Adult colony-stock, x 300 ; 

 23, isolated animalcule with at a a conjugating migrant zooid, as delineated 

 by Ehrenberg. 



24-26. OPERCULARIA ARTICULATA, Ehr. sp., vol. ii. p. 711. 24, Portion of adult colony- 

 stock, x 150; 25, isolated zooid; 26, distal extremity showing membranous 

 collar c, and stalked ciliary disc more highly magnified ; e e, kidney-shaped 

 corpuscles of undetermined nature (after Stein). 



27. OPERCULARIA BERBERINA, Linn, sp., vol. ii. p. 711, x 200 (Stein). 



28, 29. VORTICELLA ANNULARIS, MiiU., vol. ii. p. 689. 28, Group, natural size, attached 

 to a small Planorbis j 29, isolated zooid, x 10 (O. F. Miiller). 



30. ZOOTHAMNIUM MACROSTYLUM, D'Udk., vol. ii. p. 699. Dimensions unrecorded 

 (D'Udekem). 



31, 32. OPERCULARIA sp., apparently allied to O. stenostoma, vol. ii. p. 712. 31, Frag- 

 ment of colony-stock; 32, isolated zooid, as figured by Henry Baker, 

 ' Employment for the Microscope,' 1785, pi. xiii. figs. 13 and 14, dimensions 

 unrecorded. 



