358 mu sci. 



assume its form, the operculum becomes more and more and 

 more distinct, as well as its future line of separation. 



The columella increases in size upward, and soon occupies 

 the whole excavation being continued up, even to, or towards 

 the apex of the operculum, with which it is there continuous ; 

 up to this time no rudiments of a peristome were observed. 



The only change that in the mean time has taken place in 

 the calyptra, is its becoming split along its under side, in the 

 direction of the greatest pressure. 



The chief points of enquiry are now to ascertain whether 

 any charge takes place in the male organs, and whether it 

 is simultaneous or nearly so with those occuring in the female. 



Whether the apex of the female is ever perforated, and 

 whether the vesicle exists prior to the supposed impregnation. 



To examine most minutely, and in detail, all the female or- 

 gans, and why the change is limited to one. 



With regard to the developement of the theca, to ascer- 

 tain 



When the peristome first appears, and what are the steps 

 in its formation 



Which is formed first, the inner or outer ? 



On what does its presence depend : for Gymnostomum has 

 an inner membrane lining its theca. 



What becomes of the opercular part of the columella, in 

 Diphyscium, it is persistent, is not the membrane of Schis- 

 tostega and Leptostomum etc owing to its apex, adhering witli 

 the circumference of the stoma ? 



In such cases the operculum is generally Flat : except in 

 Hymenostomum. 



What is the nature of the membrane of Polytrichum ? 



On what does the annulus depend ? 



Trematodon lonyicaulis. PI. CXI. 



1 . Male flower ! aggregate terminal. 



2. One of them separated. 



