xl 



EXPLANATION OP PLATE I. 



ILLUSTRATING 



MR. ARCHER'S PAPER ON PALMOGLCEA (Kiitz.) (p. 12), COSMARIUM 

 (Corda) (pp. 49 and 66), PENIUM, (Bre"b.), (p. 50), AND ARTHRODESMUS 

 (Ehr.), (p. 67). 



Figs. 1 to 19. Mesotanium chlamydosporum (de Bary). 



Fig. 1. Cell in which the chlorophyll-plate is covered and hidden by the remain- 



ing contents. 



„ 2 to 4. Cells showing edge views of chlorophyll-plate. 



„ 5. Cell about to divide. 



„ 6. Cell dividing. 



,, 7. Two cells approaching to become conjugated. 



i, 8. Ditto, do. do., , and casting off the outer 



cell-walls. 



„ 9 to 14. Conjugated cells in different positions, the zygospore more or less ad- 

 vanced. 



,, 15 to 19. Mature z} r gospores. 



Figs. 20 to 31. ITesotcenium mirijicum (Arch., sp. nov.). 

 „ 20. Cell showing edge view of chlorophyll-plate. 



„ 21 to 23. Emergence of cell-contents by a lateral special opening, produced by the 



raising up of a lid-like portion of the cell- wall. 

 ,, 24 to 25. Cell-contents emerged, and massed into a brown spore-like body. 

 ,, 26 to 31. Various empty cell- walls, showing the various positions of the opening. 



Figs. 32 to 33. Cosmarium exiguum (Arch., sp. nov.). 

 „ 32. Cell with contents, seen in front view. 



„ 33. Outline of side view. 



Figs. 34 to 44. Penium Hooreanum (Arch., sp. nov.). 

 „ 34. Cell seen in front view. 



,, 35. Dividing cell, surrounded by a definite gelatinous investment. 



„ 36 to 38. Conjugating cells. 



,, 39. Zygospore, fully formed, seen in its front or broad view. 



„ 40. Same seen in side view. 



,, 41. Same seen in end view. 



„ 42 to 44. Zygospores, as occasionally found, somewhat twisted or distorted. 



Figs. 45 to 49. Cosmarium pygmceum (Arch., sp. nov.). 

 ,, 45 to 46. Cells seen in front view. 

 „ 47. Cell seen in side view. 



„ 48. Cell seen in end view. 



m 49. Zygospore, with still adherent empty walls of the old pair of cells. 



Figs. 50 to 55. Arthrodesmus tenuissimus (Arch,, sp. nov.). 

 „ 50. Cell seen in front view. 



,,51. Same in side view.] 



,, 52. Same in end view. 



„ 53 to 54. Dividing cells. 



,, 55. Abnormal growth, the intervening portion forming a single cavity with the 



old segments, no septum having been formed. 



