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exiguus the same as F pusillus var. Lylei Wils , or F viridulus var. 
Lylei (Wils.) Dixon.' This reference to at least three species and two vari- 
eties, along with specific rank besides, shows much diversity of opinion, and 
that it may be less confusing to leave them as Sullivant had them. 
Both are quite similar in habitat, the most common the dry channels of 
brooks and rills as I have seen them. F. minntulus I have also collected on 
stones in damp places of woods or on ledges of rock by larger streams. The 
desiccated condition of the more common habitat favors their fruiting in mid- 
summer, since the stream beds are without running water, though it may 
remain in pools; the localities are therefore moist and commonly shaded. F. 
minutulus is apt to adhere very closely to a rock substratum. There maybe 
no more appearance of a soil beneath it other than of the disintegrated rock 
than in somecrustaceous lichens, or some species of Orthotrichum and Grim- 
mia. There seems to be no choice of mineral constituents, for the stones and 
pebbles are of the various kinds washed from the drift in which the channels 
are cut. When on ledges they have been calcareous, which may be because 
the localities commonly accessible to me are of limestone formation. It is 
also apt to be unassociated with other mosses. F. exiguus I have found 
associated on clay with Amb ly ste gium v arium . 
Both species are dioicous, the male flowers mostly on shorter plants, 
which are sometimes little more than buds provided with rhizoids and con- 
cealed in the rhizoids of the larger fertile or sterile stems. In this they dif- 
fer from F. incurvus, of which they have been made a variety, and which is 
described by most authors as autoicous, though Roth makes it dioicous. 
Warnstorf gives it as both dioicous and autoicous. They may be deceptive 
in this respeet. The male flowers on the short basal branches may be well 
furnished with rhizoids and easily detached by the slightest force. When 
this happens accidently pr spontaneously the male flowers will appear as lit- 
tle stems among the rhizoids of the fertile plants, as in the case of F niinu- 
.tulus. When well advanced in growth there is apparently no vital connection 
with the parent plants even when remaining in place. From this experience 
with them I have been led to infer that the male organs may start as buds in 
the axils of leaves of fertile stems and become independent actually or appar- 
ently, or show a pseudo-dioicous inflorescence, which may account for some 
of the discrepancies. 
The principal distinction between F minutulus and F exiguus has been 
found in the character of the leaf-margin. It is called immarginate in the 
latter; I have not found this quite exact. There are two types of border in 
Fissidens, one of linear cells that may be cord-like and not always firmly 
united to the cells of the body of the leaf. F. bryoides is one of the best 
examples. With it are classed minutulus , incurvus and inconstans. The 
other type has a row or band of cells less or but slightly chlorophyllose and 
consequently less deeply colored and more translucent than the remaining 
cells of the leaf, or they may be differently colored with some tinge as of yel- 
low. They are also in general more uniform in size and shape. This kind 
of margin varies from a single row of cells to a band or zone four or five cells 
wide. The wide yellowish form is seen in F cristatus and F cidiantoides ; 
