758 MINNESOTA BOTANICAL STUDIES. 



Monoecious, like the species; simple or branching, one 

 of the branches usually terminating in the antheridial, the 

 other in the archegonial bud; leaves crowded toward the 

 top of the stem into a tumid bud, rapidly reduced to scales, so 

 that the stem below the middle is nearly naked; leaves not dis- 

 tinctly spoon- shaped under the hand lens as in the Colorado 

 plant. 



The examination into the occurrence of the sexual organs of 

 the two forms of Coscinodon wrightii shows no essential differ- 

 ences between the two plants. I have made drawings of both 

 organs with adjacent leaves also of the Colorado plant, which, 

 on comparison with those taken from the Colorado plant, show 

 incidentally that the hair points of the archegonial leaves are 

 developed before the lamina; while the antheridial leaves are 

 principally laminae with only a short costa, or with none at 

 all, and may or may not have an incipient subula, or a short 

 acumen. 



In closing, I give my diagnosis of the North American species 

 of Coscinodon so far as known at present: 



Genus Coscinodon. Leaves appear as in Grimmia; but the capsule 

 is half 'covered by a mitrate folded calyptra as in Orthotrichum. 



1. Plants dioecious, G. pulvinatus. 



Alaska, British Columbia. 



2. Plants monoecious, 



a. Costa in cross section deeply furrowed, stem leaves diverging 



and appearing keeled under a hand lens, - - C. raui. 

 Arizona, Colorada, South Dakota, Minnesota. 

 aa. Costa in cross section not furrowed, either equally projecting 

 above and below the lamina, or in upper part of the leaf re- 

 stricted to the back, 



b. Developed fruiting stems equally leafy to near base, the leaves 



to below middle of stem hair-pointed, and under hand lens dis- 

 tinctly spoon-shaped, - - - - - G. wrightii. 



Colorado, North Dakota. 



bb. Developed fruiting stems leafless for some distance above the 



rooting base, only some closely appressed scales representing 



the leaves there; hair-pointed leaves all crowded to near the 



top; no distinct appearance of spoon-shaped leaves, 



C. wrightii var. brevis. 

 Minnesota. 



