lO-II. 



12. 

 13 



PLATE XXVI. 



EXPLANATION. 



Fig. , . , , 



1-9. Opalina RANARUM,Purkinge,vol. ii. p. 559.— I, Adult animalcule, x 100 ; 2-5, 

 successive phases of segmentation terminating m the production of mmute 

 ovate zooids possessing but a few nuclei or endoplasts, X 100; 6, succeeding 

 encysted condition of No. 5, X 200 ; 7 and 8, successive developmental phases 

 of zooid that has re-emerged from the encysted state, the one at 7 possessing 

 but a single endoplast, and that at 8 three such structures, the lowermost 

 of which, at a, is in the act of subdividing; 9, a young zooid with ragged 

 pseudopodium-like lateral extensions (1-8 after Ernst Zeller, 9 after T. W. 

 Engelmann). 



Opalina obtrigona, Stein, vol. ii. p. 562.— 10, Adult zooid, x 100; 11, minute 

 encystment, X 200 (Ernst Zeller). 



Anoplophrya naidos, Duj. sp., vol. ii. p. 563.— Adult zooid, x 200 (Ray 

 Lankester). 



Anoplophrya filum, C. & L., vol. ii. p. 567, x 120 (ClaparMe & Lachmann). 



14. ANOPLOPHRYA PROLIFERA, C. & L., vol. ii. p. 564.-Adult example with five 

 incompletely separated posterior segments, x 120 (Clap. & Lach.). 



15. HOPLITOPHRYA LUMBRICI, Duj. sp., vol. ii. p. 57 L— Adult zooid in the act of 



dividing by transverse fission, at u, u, horny uncmi, x 200 (Stein). 

 16-18. OPALINA DIMIDIATA, Stein, vol. ii. p. 561.-16, Adult animalcule, x 100; 17, 

 minute zooid, produced through successive fission of adult unit, commencing 

 to subdivide again in a longitudinal direction ; 18, elongate zooid, containing 

 but a single endoplast, recently emerged from a minute encystment (Ernst 

 Zeller). 

 19. Opalina intestinalis, Ehr. sp., vol. ii. p. 562, x 100 (Ernst Zeller). 



OPALINA ranaruM, Purk., vol. ii. p. 559.-Fragment of cuticular fibrillae treated 



with acetic acid, x 200 (Zeller). 

 ANOPLOPHRYA CLAV ATA, Leidy sp., vol. ii. p. 566, X 150 (Leidy). 

 HOPLITOPHRYA RECURVA, C. & L. sp., vol. ii. p. 573, X 13° (Clap. & Lach.). 

 23, 24. OPALINA CAUDATA, Zeller, vol. ii. p. 563.-Dorsal and lateral aspects, x 120 

 (Zeller). 

 25 ANOPLOPHRYA COCHLEARIFORMIS, Leidy sp., vol. ii. p. 566, X 150 (Leidy). 

 26, 27! ANOPLOPHRYA MYTILI, Qucnn. sp., vol. ii. p. 565.-Lateral and dorsal aspects, 



X 250 (Quennerstedt). 

 28-30. PARAMECIUM AURELIA, Miiller, vol. ii. p. 483--28 and 29, Lateral and ventral 

 aspects, X 200 ; 30, two conjugating zooids. 



20. 



21. 



22. 



