52 PROCEEDINGS OP THE AMERICAN ACADEMY 



Plate IV. 



Figs. 23-25. Heppia Despreauxii, (Mont.) Tuck. Asci and paraphyses. X 1100. 

 Figs. 26, 27. Hydrolhijria venosa, Russ. Asci and paraphyses after treatment 



witli iodine. X 500. 

 Figs. 28-30. Hydrothyria venosa, Russ. Young paraphyses with bridge-like 



connections. X 600. 



Plate V. 

 Hydrothyria venosa, Russ. 

 Fig. 31. Cross-section of vein and portion of thallus. X 140. 

 Fig. 32. Cross-section of double apotheciura. Freehand drawing. 

 Fig. 33. Isolated gonidia. X 1025. 



Plate VI. 



Fig. 34. Physma byrsceum, (Afzel.). Cross-section of a thallus 0.9 mm. thick, 



showing only the upper and lower surfaces. X 140. 

 Fig. 35. Physma luridum, (Mont.). Cross-section of thallus. X 140. 



Plate VII. 



Fig. 36. Collema chalazanum, Ach. Cross-section of young apothecium, with 

 trichogynes. X 140. 



Fig. 37. Physma Mulleri, Hepp. Cross-section of young apothecium occupy- 

 ing a spermogonial cavity with portion of a trichogyne. X 140. 



Plate VIII. 



Fig. 38. Leptogium myochroum, (Ehrh., Schaer.) Tuck. Ascogonium and 

 portions of two trichogynes. X 500. 



Fig. 39. Collema pulposum, [Bernh.) l^yl. Ascogonium. X 500. 



Fig. 40. Collema nigrescens, [UnAs.) Ach.. Young ascogonia. X 500. 



Fig. 41. Collema nigrescens, (Huds.) Ach. Older ascogonium partially envel- 

 oped by the surrounding hyphae. The hyphse which rise toward the upper 

 surface of the thallus already show a definite parallel arrangement. X 500. 



