82 THE JOURNAL OF BOTANY 



the peristome for the purpose of drawing up a diagnosis, a some- 

 what striking peculiarity presented itself, differing from anything I 

 could find in descriptions of the peristome in Splachnobryum. It 

 became desirable to compare this structure in other species, but 

 mature capsules in this genus are extremely difficult to obtain, and 

 it was only after considerable delay, and after, I fear, taxing the 

 kindness of numerous correspondents, that I was able to obtain 

 suitable material for comparison ; and even now I am quite unable 

 to say whether the particular structure in question is peculiar to 

 the plant under consideration, or whether it may be shared by 

 some other species of the genus. In any case, however, it has been 

 so far undescribed, and is of sufficient interest to call for notice ; 

 but involving as it does the somewhat complicated and not generally 

 understood composition of the peristome-teeth in Splachnobryum, it 

 is necessary to enter into some detail. 



The general structure of the teeth in Splachnobryum has been 

 described by Philibert (Rev. Bry. 1890, p. 9) in the course of his 

 admirable series of " Etudes sur le Peristome." The description 

 rests upon S. Boivini C. M., the only species of which he was able 

 to obtain specimens showing this structure. 



The peristome in S. Boivini consists of sixteen narrow teeth, 

 always inserted (a character constant in the genus) at a considerable 

 distance below the mouth of the capsule, and so short as to protrude 

 but little above it. The portion visible above the orifice consists of 

 sixteen narrow, papillose teeth, each with a median line from top 

 to bottom, and resembling closely the less highly developed peri- 

 stome of many of the Pottioid mosses. The lower concealed part 

 of the teeth, however, which is frequently fully equal in length to 

 the exserted portion, is considerably more complex. A longitudinal 

 section of the capsule, or a transverse section just below the orifice, 

 shows three concentric layers of cells; the outer, forming the 

 capsule-wall, consists of cells considerably elongated in the radial 

 direction, with the outer walls strongly incrassate, and coloured a 

 deep reddish brown, the inner walls being much thinner and paler. 

 Within this row is a ring (as seen in transverse section) of thirty- 

 two cells, much narrower in the radial direction. This ring repre- 

 sents the layer of cells from the innermost walls of which, in the 

 normal peristome of the Diplolepidea, the dorsal plates of the outer 

 teeth are derived, the outer and lateral walls of each cell and a part 

 at least of the upper and lower walls being absorbed, while the 

 inner wall is thickened and remains to form the outer (dorsal) 

 plates; each adjoining pair of the thirty^two cells goes to form one 

 of the sixteen teeth, which appears therefore divided down the 

 middle by a fine median, often zigzag line. In the case of o. 

 Boivini, however, while the inner walls are more or less thickened, 

 the remaining walls of these cells do not (in the part of the 

 peristome below the orifice) become absorbed and disappear, but 

 remain ; they are not, however, thickened or highly coloured. 



The cells of the third ring or layer are (in S. Boivini) slightly 

 longer in their radial diameter than in the preceding layer ; their 

 walls also persist in their entirety, and thus form a series of close 



