PARASITISM OR POLYMORPHISM — WHICH ? 83 



pacted mass of fine threads, only distinguishable when crushed in 

 water under the microscope (fig. 14), branching out at the summit, 

 and giving off a vast number of minute spores too small to admit 

 of accurate measurement, which are held together by some 

 glutinous substance forming the head (fig. 14 a). Extending up 

 the stem, and branching from it at different intervals (fig 13 c, c), 

 either as natural growth or parasitic growth, were what exactly 

 corresponded to what I have called above Monotospora sphcerocephula, 

 B. & Br. (fig. 15). I tried to trace some difference in the threads 

 composing the stem of the Stilbum, but was unsuccessful, and I am 

 quite unable to say whether they exist or not. Tliis association of 

 growth of four dift'erent species appeared so curious in some particu- 

 lars that I have thought it well to place the facts before your readers. 



DESCRIPTION OF PLATE uri. 



Fig. 10. — A magnified group of black moulds X 7" linear, a, a, Monotospora 

 sphwrocephala, B. &Br., M. megalospora, B. & Br., and Helmintho- 

 sp irium obovatiim. Berk. 



Fig. 11. — The same magnified 284. 



Fig. 12 — The heads in ihe suggested order cf growth. 



Fig. 13 — Siilbum >'igidum, P , with Monotospora sphoerocepliala growing from 

 its ?tem X 75- 



Fig 14.— The head of Stilbum rigidum, P. X 284- 



Fig. 15. — One of the branches from Stilbum rigidum , magnified 284. 



BRITISH LICHENS. 



In the Journal of Botany for May, Mr. Crombie records the 

 following additions to the British Lichen Flora: 1. Fi/renopsis 

 phylliscella, Nyl. sp. n. 2. CoUe7nopsis oblongans, Nyl. sp. n. 3. 

 Collema tenulentum, Nyl. sp. n, 4. C. graimUferuin. Nyl, sp. n. 

 5. Pilophoron strumaticum, Nyl. sp. n. 6. Alectona sarmentosa^ 

 Ach. 7. Parmelia sulcata, var. Icevis, Nyl. f. hirsuta, Cromb. 8. 

 Phyecia tribacoides, Nyl. sp. n. 9. Lecanora subexigna, Nyl. sp. n. 

 10. Lecanora leucophceiza. Nyl. sp. n. 11. L. austei^a, Nyl. sp. n. 

 12. L. subcinerea, Nyl, 13. L. cinerea, f. lepidota^ Leight, 14. 

 L. fuscescens i^ViWiVcl.) 15. L. Bischoffii {Jie]^-p.) 16. Pertusaria 

 xanthostoma (Smmrf.) 17, i ecidea 2n'asiiuza, Nyl. 18. Lecidea 

 Ivbens, Nyl. sp, n. 19, L. ochracea (Hepp.) 20 L. scopulicola, 

 Nyl, sp. n, 21. L. phylliscina, Nyl. 22, L. phyUiscocarpa,^j\. 

 sp, n, 23. L. dealbatida, Nyl, sp, n, 24. L. sorediza, Nyl.* 25. 

 L. confuswr, Nyl, sp, n, 26. L. luteo-atra, Nyl, 27. L. 7ieglecta, 

 Nyl, 28, L. advejiula, Leight. 29, L. iirceolata, Ach. 30. Xy- 

 lographa laricicola, Nyl. sp, n. 31, Ptycliographa xylographoides, 

 Nyl. sp. et gen. n, 32. Arthonia xmnctiliformis, Leight, sp. n. 

 33. Melaspilea vermiformis, Leight, sp. n. 34. Thelocarpon 

 superellum, Nyl, 35. Verrvcaria flnctigena, Nyl. sp, n. 36, 

 Obryzum cornicidatum, Wallr. 37, Endococus triphractoides, Nyl, 

 sp, n. 



* This = Mudd exs, n. 181. not L. suhconfluens, Th. Fr, Scand, p. 487 (excl. 

 Syn. Mudd), which is sufficiently distinct. 



