Mr. Brown on Lyellia, Leptostomum, and Biixbanmia. 577 



sence of the annulus ; and the insertion, form and relative position 

 of the male flowers, whicli, though always considered of import- 

 ance by Hedwig, many of the most distinguished muscologists 

 of the present day entirely exclude from the characters of their 



genera. 



With respect to the principal sourceof generic distinctions, the 

 Peristomium, in addition to the circumstances generally attended 

 to, namely, the origin, number, direction, form, and actual divi- 

 sion of the teeth, it may be of some importance to ascertain their 

 jEstivation, which, though very generally, is not always valvular: 

 and especially to mark the existence or want of the longitudinal 

 stria ox semi-pellucid lines: for these, if they do not prove the 

 compound nature, at least clearly indicate a tendency to division 

 in the teeth where they are found ; division being always in the 

 course of the striae, and in no instance taking place unless where 

 they are present. 



But in considering them, which I am inclined to do, as proving 

 composition or confluence of the teeth, it would appear that there 

 is a much greater uniformity in the structure of the simple or outer 

 peristomium, afleast, than is generally admitted; and that the 

 prevailing number of teeth in this series is thirty-two ; though by 

 a coalescence, more or less complete, they are frequcnily reduced 

 to sixteen, in some cases to eight, and in a few even to four. 



Accordino- to this view, a single longitudinal line in the axis of 

 a tooth indicates the confluence of two teeth; three equidistant 

 lines, one being- central, the coalescence of four ; and seven lines 

 similarly dispciscd that of eight. 



Nearly the whole of those modifications exist in that natural 

 subdivision of the order, which may be named Siifachnect, consist- 

 ingof Splachnum, Sijstijlium, Tayloria, (Hoo/cer/a of Schwaegrichen,) 

 Splachnum squarrosum of Hooker, and JFeissia splachnoides. 



The 



