Snow. — P seudo-P lenrococcus , Nov. gen . 
195 
Literature. 
1. Artari, A. : Untersuchungen iiber Entwickelung und Systematik einiger 
Protococcoideen ; Inaug. Diss., Moskau, 1892. 
2. Chodat, R. : Materiaux pour servir a l’histoire des Protococcoidees ; Bull, de 
l’Herbier Boissier, 1894. 
3. Chodat, R. : On the Polymorphism of the Green Algae and the Principles 
of their Evolution ; Annals of Botany, Vol. XI, No. 41, 1897. 
4. Gay, Fr. : Recherches sur le developpement et la classification de quelques 
Algues vertes ; Paris, 1891. 
5. Klebs, G. : Die Bedingungen der Fortpflanzung bei einigen Algen und Pilzen ; 
Jena, 1896. 
EXPLANATION OF FIGURES IN PLATE XL 
Illustrating Miss Snow’s paper on Pseudo-Pleurococcus. 
All figures were drawn with an Abbe camera. In all figures except Fig. 16 
a 3 mm. Zeiss apochromatic objective and a No. 6 compensating ocular were used. 
In Fig. 16 the same ocular was used, and an 8 mm. lens. 
Pseudo- Pleurococcus botryoides , Nov. sp. 
Figs. 1-6. Different stages found on bark. 
Figs. 7, 8. Development of unicellular stage into filamentous stage. 
Figs. 9-12. Development of unicellular stage into parenchymatous stage. 
Fig. 13. Development of filamentous stage into parenchymatous stage. 
Figs. 14, 15. Development of parenchymatous stage into filaments. 
Fig. 16. Filamentous stage from liquid medium. 
Pseudo- Pleurococcus vulgaris , Nov. sp. 
Figs. 17, 18. Clusters with filaments in different stages of development. 
Fig. 19. Beginning of transition from filamentous to parenchymatous and 
unicellular stages. 
