348 Hints on the Study of Hepatics. [Sess. 



latter being popularly termed scale-mosses. The frondose 

 species are prostrate, frequently forming large patches on soil 

 and on wet rocks, one or two species also being found on trees. 

 The only other plants with which they can be confused are 

 some of the lichens, but those lichens having any resemblance 

 to hepatics are thin and leathery, while the latter are more or 

 less fleshy, or have a midrib running along the frond. The 

 most common species of the frondose section, Pellia epiphylla, 

 may easily be examined by the beginner. It is found on the 

 sides of ditches and on moist soil generally, and fruiting 

 abundantly in March and April. The capsules are borne on white 

 pedicels, two to three inches in length. In a day or two the 

 capsules split into four valves, exposing the spores and some 

 spiral threads, which are termed elaters. The base of the 

 pedicel will be seen to be enclosed in a white membrane, 

 named the calyptra, and outside this membrane the frond 

 appears raised except at the part nearest the apex of the 

 frond. This raised part is the involucre. In our two other 

 species of this genus the involucre forms a complete ring, the 

 part nearest the apex of the frond not being absent. Instead 

 of having a solitary capsule at the end of a pedicel as in 

 Pellia, the species of another division of the frondose species 

 have several capsules together, on the underside of a stalked 

 receptacle, as in the familiar " umbrella " heads of Marchantia 

 polymorpha. Most of the species in this latter division have 

 a conspicuous network on the upper surface of the frond. 

 Another family, the Eicciacese, of which Eiccia sorocarpa is 

 frequent in gardens and fallow fields in autumn, has the 

 capsules embedded in the fronds. 



The other great section of the Hepaticse, containing the 

 foliose species, comprises the great majority of our genera and 

 species. In most of them the leaves appear as if arranged 

 horizontally on two sides of the stem. A few mosses have 

 also this appearance, and are frequently mistaken for hepatics 

 by beginners. The genera of mosses thus confused are 

 Plagiothecium, Pterygophyllum, and Fissidens. A glance 

 through the microscope will show that the two former have 

 long and narrow leaf -cells, which never are found in the 

 leaves of hepatics. Species of Fissidens have a midrib run- 

 ning along the leaf, which structure does not occur in the 



