a primitive Lichen. 585 
cells, often proliferating inwardly, including the green algal cells, the latter 
forming either a central green mass or occurring more sparingly scattered 
in the interspaces between the fungus cells. 
The alga is Coccomyxct siibellipsoidea , one of the Palmellaceae. The 
fungus belongs to the section Helicosporae of the family Mucedineae. 
Its natural habitat is in damp shady situations among various Bryo- 
phytes, generally on rocks, but sometimes on damp ground. It is not 
uncommon in the mountainous districts of the British Islands, and occurs 
among a variety of Mosses and Hepatics . 1 
DESCRIPTION OF PLATE XLIV. 
Illustrating Miss Acton’s paper on Botrydina. 
Fig. 1. Shoot of Campylopus Jlexuosus covered with Botrydina. x 30. 
Fig. 2. Thallus of Botrydina showing envelope with attached hyphae. x 1000. 
Fig. 3. Thallus showing arrangement of green cells in interior, and attached fungal hypha- 
x 1000. 
Fig. 4. An early stage. The algal cells have been invested by the fungus, but no septa have 
appeared, x 1 000. 
Fig. 5. A later stage showing septa, x 1000. 
Fig. 6. Algal cells. <2, shows oblique division; b , distorted form; c, typical cell with re- 
fractive granules, x 1000. 
Fig. 7. Section through a thallus. The interior is filled with algal cells lying in mucilage, 
x 1000. 
Fig. 8. Portion of a large thallus. The interior consists almost entirely of fungal cells. A few 
algal cells are shown, x 1000. 
Fig. 9. Portion of a thallus from which the green cells had disappeared, with hyphae growing 
out from two adjacent cells, x 1000. 
Figs, io-ii. Young specimens with no attached hyphae. x 1000. 
1 It occurs in many parts of West and North-West Yorkshire, and has been noticed more 
particularly among Tetraphis pellucida and Leucobryum glaucum (vide W. and G. S. West, ‘ The! 
Alga-flora of Yorkshire,’ Trans. Yorks. Nat. Union, vol. v, 1901, p. 129). 
