EXPLANATION OF PLATE XXXIX. 



Fig. f , , 



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 1°° (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. 7I4-— 9i Expanded, 10 and 11, 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 ; aiaaa, 

 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 (ClaparSde & 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. 7 1 3.— 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 fl 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, Midi., vol. ii. p. 689.-28, Group, natural size, attached 

 to a small Planorbis; 29, isolated zooid, x lo (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. 



