EXPLANATION OF THE PLATES. XXI 



6. Discelium nudum. 



a. plant, nat. size. 



b. leaf, magnified. 



c. sporangium, magnified. 



d. peristome with ring and spores, magnified. 



7. Catoscopium nigritum. 



a. plant, nat. size. 



b. leaves, magnified. 



c. sporangium, magnified. 



d. portion of peristome, magnified. 



8. Conostomum boreale. 



a. plant, nat. size. 



b. sporangium, magnified. 



c. portion of peristome, magnified. 



d. portion of one of the teeth, magnified. 



e. leaf, magnified. 



PLATE XVI. 



1. Bartramia ithyphylla. 



a. plant, nat. size. 



b. leaf, magnified. 



c. sporangium, magnified. 



d. portion of peristome, magnified. 



2. B. pomiformis. 



a. plant, nat. size. 



b. leaf, magnified. 



c. leaf-cells and margin, magnified. 



d. sporangium, magnified. 



e. portion of peristome, magnified. 



3. B. (Ederi. 



a. plant, nat. size. 



b. leaf, magnified. 



c. sporangium, magnified. 



