Lang. — On the Morphology of Cyathodium. 
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EXPLANATION OF FIGURES IN PLATES XXI AND XXII. 
Illustrating Dr. Lang’s paper on the Morphology of Cyathodium. 
PLATE XXI. 
Cyathodium foetidissimum . 
Fig. 1. A plant of Cyathodium foetidissimum viewed from below: the thallus has branched 
dichotomously ; an antheridiophore is seen some distance from the anterior margin of each branch, 
and between it and the margin there are in each case a pair of involucres enclosing sporogonia. 
X 42- 
Fig. 2. Portion of the thallus bearing two adventitious branches. 
Fig. 3. One of the adventitious branches seen from above, showing its relation to the margin of 
the thallus. x 44. 
Fig. 4. Ventral scales, a, b, reduced forms from the base of an adventitious branch ; c, the 
normal form from the well-developed thallus. x 200. 
Fig. 5. Transverse section of the thallus in the region of the midrib ; the shaded cells were 
occupied by Fungal hyphae. x 200. 
Fig. 6. Two cells of the ‘ epidermis ’ in vertical section, showing the position of the chloro- 
plasts in the convexity of the cell, x 353. 
Fig. 7. Cells of the ‘ epidermis ’ in surface view ; the small cell in the centre contains an oil 
body, the others are assimilating cells, x 353. 
Fig. 8. Medium longitudinal section of the apex of a vegetative branch, x 250. 
Fig. 9. Fertile branch seen from below, showing a mature antheridiophore and in front of it 
large ventral scales covering over the groups of archegonia. x 46. 
Fig. 10. Longitudinal section of a specimen of the same age as that in Fig. 9, passing through 
the shortly stalked antheridiophore, and showing the apical cell displaced towards the lower surface 
and in front of it two young archegonia. x 200. 
Fig. 11. Longitudinal section of a mature antheridium. x 530. 
Fig. 12. Longitudinal section through the upper part of an antheridium and the opening of the 
chamber of the antheridiophore that contained it. x 353. 
Fig. T3. Sketch showing the position of the developing archegonia and of the V-shaped ridge 
marking the junction of dorsal and ventral surfaces in the region of the displaced apex. 
Fig. 14. Longitudinal section through an apex bearing a fully formed group of archegonia ; the 
apex has commenced to form the hinder portion of the involucre, x 80. 
Fig. 15. Series of developmental stages of the archegonium in longitudinal section, x 640. 
Fig. 16. View of fertile branch from below, showing the spent antheridiophore and in front of 
it two fully developed involucres ; that on the right is occupied by two sporogonia, while the one on 
the left contains unfertilized archegonia. x 23. 
Figs. 17-19. Three stages in the development of the sporogonium. x 375. 
Fig. 20. Median section of a sporogonium with isolated spore-mother-cells; the calyptra 
enclosing it is shaded, x 130. 
Fig. 21. Longitudinal section of the base of the calyptra, showing the absorbent processes 
developed from the basal cells of the foot of a sporogonium which contained tetrads, x 250. 
Fig. 22. Cross section of stalk-like portion of foot, x 375. 
Fig. 23. Cross section of basal portion of foot, showing the absorbent processes, x 250. 
Fig. 24. Nearly median section of a mature sporogonium ; the apical cap of cells is not seen, 
x 136. 
PLATE XXII. 
Cyathodium cavernarum. 
Fig. 25. Plants of C. cavernarum. a , sterile plant; 3, plant bearing three archegonial groups 
and two antheridiophores. x 7. 
Fig. 26. Two of the larger ventral scales, x 200. 
Fig. 27. Vegetative apex seen from below, showing the shape and mode of segmentation of the 
apical cell, x 670. 
