290 EXPLANATION OF PLATES. 
Prats X. . 
Illustrative of the genera Puatysma, Hoffm., Nyl.; Ricasoz1a, DN., Nyl.; and Sricra, Ach. 
Fig. 1. Platysma ciliare, Ach.; Schooley’s Mountains, North America. Showing the marginal 
denticulate spermogones a, 
Fig, 2. Portion of edge of thallus magnified, showing the barrel-shaped spermogones : 4, ostiole. 
Fig. 3. Sterigmata a and spermatia b of same species. 
Fig. 4. P. lacunosum, Ach., var. 6 atlanticum ; Tuckerman exs., 6. Portion of thallus, showing the 
marginal button-shaped spermogones a. 
5. Portion of edge of thallus, magnified to show the marginal spermogones a. 
es 
ge 
Fig. 6. Ricasolia herbacea, DN., Inverary. Portion of thallus, showing a, apothecia; and 6}, 
papilleform or mammilleform spermogones. 
= 
19 
~I 
. Two of the spermogones more highly magnified, showing a, a simple ostiole; and 6, a 
stellate-fissured ostiole. 
Fig. 8. Section of thallus, showing a, an apothecium; b, mammillar spermogones. 
Fig. 9. &. herbacea, from Sikkim, Himalayas. Portion of thallus, showing marginal tooth-like 
spermogones a, as well as the ordinary mammilleform ones 6. 
Fig, 10. Two of the same marginal spermogones more highly magnified : a, ostiole. 
Fig. 11. R. herbacea, Sterigmata a and spermatia 6. 
Fig. 12. R. glomulifera, DN.; Inverary. Portion of thallus, showing a, apothecia; 6, mammille- 
form spermogones ; and ¢, a “ glomerulus.” 
Fig. 18. Sticta glabra, Tayl.; Falkland Islands. Portion of thallus, showing a, apothecia; and 
b, papilleeform spermogones. 
Fig. 14. Sections through thallus, showing the spermogones in different phases of development: a, 
body of spermogone ; 8, papilleform ostiole. 
Fig. 15. S. linearis, Tayl.; Tasmania. Portion of thallus, showing a, apothecia; and 6, brown 
punctiform immersed spermogones, scattered chiefly on the ruge. 
Fig. 16. S. damecornis, Ach., var. macrophylla, Hook. ; Killarney. Portion of thallus, showing 
a, apothecia; and b, mammilleform spermogones. 
Fig. 17. Two of the same spermogones, isolated and magnified to show a, a simple ostiole—young ; 
and }, a stellate-fissured ostiole—old. 
Fig. 18. Section of one of the same spermogones. 
Fig. 19. Sterigmata a and spermatia b of the same lichen. 
Fig. 20. S. flavicans, Tayl. ; Falkland Islands. Portion of thallus, showing the sub-marginal 
papilleform spermogones a, and the bright-yellow medullary tissue appearing in a 
fissure of the cortical layer of the thallus at b. 
Fig. 21. Portion of another specimen of same plant, showing both papilleform @ and punctiform 
b spermogones ; the latter occurring chiefly on the rugz of the thallus. 
Fig. 22. Section of thallus, showing both papillzform a and punctiform 6b spermogones. 
Fig. 23. S. orygmea, Ach.; Auckland Islands. Portion of thallus, showing a, apothecia; and 6, sub- 
papilleeform spermogones, seated both on the rugee and about the margins of the thallus. 
Figs. 24 and 25. Sections of thallus, showing a, an apothecium ; and 6, spermogones. 
Fig. 26. S. carpoloma, Del. (= S. impressa, Tayl.); New Zealand. Portion of thallus, showing a, 
apothecia; and b, minute brown punctiform immersed spermogones, mostly seated on 
the rugee. 
Fig. 27, Section of thallus, showing the same spermogones a. 
Fig. 28. S. filicina, Ach., var. Menziesti, Hook. fils. ; New Zealand. Section through thallus, - 
showing the spermogones a seated in cavities b of thalline papille. 
Fig, 29. S. pulmonacea, Ach.; Glen Muick, Braemar. Portion of thallus, showing the brown, 
minute, punctiform, immersed spermogones a. 

