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of the plant consists merely of a short bud-like cluster of leaves borne on an 
exceedingly short stem and surrounding the diminutive capsule. The whole 
plant in Nanomitrium is scarcely more than i mm. in height, and even in the 
larger forms of Ephemerum rarely exceeds 2 mm. One of the most import- 
ant distinguishing characteristics of these two genera, and fortunately one 
which facilitates their recognition in the field, is the fact that the green 
protonema, from which the leafy shoots arise, persists throughout the life of 
the plant. In many species, especially in those which, like Ephemertan 
spinulosum, grow in very damp places, this structure forms a conspicuous, 
dark green, felty mat, covering the substratum about the leafy shoots. It 
looks very much like a mass of Vaucheria or some other Alga, and is darker in 
color than the pale green protonema of Pogonatiim tenue. Upon close exam- 
ination of such a mat with a hand lens the fruiting plants of Ephemerum, if 
present, are easily distinguished. In some forms, however, e. g. Nano7nit- 
rium Austini, the protonema is not a conspicuous field character of the 
plant. Such species are to be detected only by digging up and carefully 
eximining with a lens pieces of earth which appear promising. 
Time of Fruiting. Both Ephemerum and Nanomitrium are annuals. 
In some species the entire life cycle from spore to spore is completed in less 
than six months. Late in summer or early in autumn the tiny, spherical 
capsules become distinguishable with a lens. The spores mature from late 
autumn to spring, so that the most favorable time for collecting the plants is 
from October to January. 
Habitat. In this connection the following list of localities from which 
some of the specimens in the writer’s possession have been collected may be 
suggestive: “fields and gardens,” “ thin soil on rocks,” “relatively dry, 
hard earth in a cart path,” “lumps of earth in old corn fields,” “gravelly 
roadsides,” “river bank,” “among marsh grasses on moist ground in river 
bottoms,” muddy bed of a dried up pond,” “dry mud at the border of a 
cattle wallow,” “ clayey bottom and sides of ditch.” It will be seen that 
their habitats are quite varied. 
In general they may be looked for on any bare, earthy substratum which 
is not too dry the year round and which has not already been preempted by 
such prolific forms as Fitnaria hygrometrica, Physcomitrium turbinatum , 
Bry7im argenteuni, Pohlia nutans, and P. proligera. They usually grow 
in sunny or only slightly shaded situations, and almost never in the woods. 
Of the habitats listed above, the last four mentioned are perhaps the most 
certain to repay close investigation. It is in such places that Riccias are wont 
to occur, and these liverworts are very frequently associated with Ephemereae 
of some description. 
Range. Largely on account of their small size the Ephemerae have been 
so little collected that it is at present impossible to describe their distribution 
with any degree of accuracy. On a basis of the stations for various species 
thus far recorded the range of the group may be roughly defined as; Quebec 
to Florida; westward to Saskatchewan, Kansas, and Louisiana; and in Cali- 
fornia. Concerning the distribution of the individual species still less is 
