PLATE XXI. 



EXPLANATION. 

 Fig. 



I. Phacus triqueter, Ehr. sp., vol. i. p. 387. — aa^ Amylaceous corpuscles; e^ 

 eye-like pigment-spot, x 600 (Stein). 



2-5. Phacus pleuronectes, Ehr. sp., vol. i. p. 386 (Stein).— 2, Normal animalcule, 

 X 600; 3, example with the nucleus or endoplast divided into four fra^-- 

 ments, those at ^^ being further separated into germinal elements, consti- 

 tuting the so-called " germ-sacs " or " germ-spheres " of Professor Stein ; 4, 

 an instance of transverse fission ; 5, indurated membrane or carapace left 

 after the decay of the enclosed body-substance. 



6, 7. Phacus longicaudus, Ehr. sp., vol. i. p. 387 (Stein).— 6, More normal form ; 

 7, spirally twisted non-flagellate example, x 300. 



8, 9. Chloropeltis hispidula, Eichwald, vol. i. p. 388.-8, Lateral, 9, ventral 

 aspect, X 600 (Stein). 



10. Phacus pyrum, Ehr. sp., vol. i. p. 387, x 600 (Stein). 



11-13. Chloropeltis ovum, Ehr., vol. i. p. 388.— « a, Amylaceous corpuscles; 13, 

 subcylindrical variety, x 600 (Stein). 



14-16. Trachelomonas volvocina, Ehr., vol. i. p. 389 (Stein).— 14, Normal type, 

 X 500; 15, animalcule with flagellum retracted, emerging from its lorica; 

 16, example bursting and liberating monadiform germs. 



17. Trachelomonas rugulosa, St., vol. i. p. 389, x 500 (Stein). 



18, 19. Trachelomonas lagenella, Ehr. sp., vol. i. p. 389 (Stein). — 19, Encysted 

 example with body divided by transverse fission, x 500. 

 20. Trachelomonas cylindrica, Ehr., vol. i. p. 390, x 600 (Stein). 



21-23. Trachelomonas hispida, Pty. sp., vol. i. p. 390 (Stein).— 21, Necked variety, 

 X 500 ; 22, neckless variety, with animalcule emerging from its lorica ; 23, 

 example with lorica invested with an outer mucilaginous covering. 



24. Trachelomonas caudata, Ehr. sp., vol. i. p. 391, x 500 (Stein). 



25. Trachelomonas armata, Ehr. sp., vol. i. p. 390, x 500 (Stein). 



26. Trachelomonas acuminata, Schmarda, vol. i. p. 391, x 450 (Stein). 



27. Trachelomonas eurystoma, St., vol. i. p. 390, x 500 (Stein). 



28, 29. Ascoglena vaginicola, St., vol. i. p. 393 (Stein).— 28, Normal form, x 500 ; 

 29, example divided by transverse fission, the anterior segment emerging 

 from the parent lorica. 



