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118 -Rhodora {June 
The projecting cells, which Douin emphasizes so strongly, are very 
striking. In extreme cases numerous cells of a superficial row pro- 
ject and form a narrow ridge, from the margin of which rounded or 
bluntly conical crenulations or denticulations arise, each consisting of 
one or two cells. All gradations occur between this extreme condition 
and that in which the projecting cells are isolated and irregularly 
scattered. No case has been observed, however, in which a stem 
was smooth for any considerable distance. It may be added that 
the walls of the cells are thin throughout. Both leaves and under- 
leaves are well developed. The leaves, which are transversely at- 
tached or nearly so, spread at an angle of sixty degrees or less and are 
more or less concave. They are bifid nearly or quite to the middle 
with acute lobes and sinus. Their cells average about 10 X 8 u and 
are thin-walled throughout. The margins of the leaves are spar- 
ingly crenulate or denticulate from projecting cells and the outer 
surface is roughened in much the same way as the stem; in other 
words it shows projecting cells, which are sometimes numerous, form- 
ing short and irregular ridges, and sometimes few and scattered. 
The underleaves are ovate and either pointed or shortly bifid at the 
apex. The margin and outer surface are much as in the leaves, 
although they tend to show fewer projecting cells. 
Aside from its rough stems C. spinicaulis is much like C. papillosa 
Douin, a species recently reported by the writer ! from Massachusetts 
and Connecticut. Although Douin implies that C. spinicaulis is the 
only species of the genus in which the stems are characterized by pro- 
jecting cells, Howe,? in the description of his Cephalozia divaricata 
scabra, which is now considered a synonym of C. papillosa, states 
that the stems exhibit “rarely here and there minute paraphyllia- 
like appendages usually composed of two or three cells in a lineal 
series." If such structures were at all abundant they might throw 
doubt on the importance of the projecting cells in C. spinicaulis as a 
specific character. They must, however, be exceedingly rare because 
the writer has found no traces of them in most of the specimens of C. 
papillosa which he has examined. Under the circumstances, therefore, 
it seems justifiable to follow Douin in emphasizing the projecting cells 
and in considering C. spinicaulis a valid species. Unfortunately both 
the specimens studied are destitute of antheridia, archegonia, and 
gemmae. 
1 Rnopona 14:222. 1912. 
? Mem. Torrey Club 7:129. 1899, 
