THE BRYOLOGIST. 
Vol. VII. 
May, 1904. 
No. 3. 
THE PERISTOME, VI. 
A. J. Grout. 
In Funaria the segments are formed by the thickening of the ventral or 
inner walls of the sixteen cells, instead of adjoining portions of two cells as 
in Mnium\ hence in Funaria the segments are directly opposite the teeth 
instead of alternating with them (See Bryologist, V., p. 6). Moreover, the 
exterior surface of the segments consists of a single row of plates instead of 
a double row, as in Mnium ; this last follows as a necessity from the position 
of the segments, but on the inner side of the peristomial layer of cells, instead 
of several irregular rows of cells there are just two rows, corresponding 
in position exactly to the two rows on the outside of the peristomial layer in 
Mnium, so that the inner face of the segments consists of a double row of 
plates like the outer surface of the teeth. 
M. Philibert suggests that the inner peristome of Bartramia may be 
intermediate between these two types, for while the segments are carinate as 
in Mnium , they are split along the keel: if now the adjoining halves of each 
pair of segments were to be united, we should have a condition strongly 
resembling that in Funaria. As there is a basal membrane which does not 
split at all this hypothesis does not seem at all forced. In Dicranum and 
most of the Aplolepideae the outer side of the teeth consists of a single row 
of plates, like the segments in Fimaria. The median line is the line of junc- 
tion of the two rows of plates which form the inner side of the tooth. For 
these reasons and some others not so easily explained, Philibert has con- 
cluded that the peristome of the Aplolepideae is homologous with the inner 
peristome of the Diplolepideae. For this reason it seems objectionable to 
speak of the endostome. 
Philibert says: 
“Mosses which have 
only a single row of 
plates on the dorsal 
surface of their teeth 
never have a double 
peristome.” 
In Tor tula szibu- 
lata (L.) Hedw. (Fig. 
1,) the peristomial 
layer is bounded on 
Fig. 1. its inner surface by 
another layer of sixteen cells, exactly matching the peristomial layer in posi- 
tion. The teeth are formed by thickenings in the four contiguous corners of 
this double row of cells. There are thus sixteen separate centers of deposit 
made up of four parts each. The thirty-two teeth of Barbula and Tortula 
The March Bryologist was issued March 5th, 1904. 
