MOSSES WITH A HAND-LENS 



165 



and a lustre as if saturated with some oleaginous compound." 

 The thallus is 1-2 inches long and | to ^ inch in width. It 

 is slightly lobed or sinuate. Spores in spring. 



JUNGERMANNIACEAE. The Scale Mosses. 



The reproductive part of the 

 Scale Mosses, including the ripened 

 capsule and its connected parts, per- 

 ianth, involucre, etc., is essentially as 

 in the Thalloid Scale Mosses, but the 

 vegetative part strongly resembles the 

 true mosses in general appearance. 

 The leaves, however, are apparently 

 flattened out into two rows, one on 

 either side of the stem. They are en- 

 tirely without midrib and are fre- 

 quently two-cleft or lobed. One of the 

 lobes is often smaller and folded under 

 the other, making the leaves " com- 

 plicate-bilobed," in the language 

 of the books; this is shown in the 

 illustrations of Radula and Por- 

 ella. This can best be made out 

 by holding a single stem up to the light and examining with a 

 lens, when the under lobe will show plainly as a deep shadow. 

 In Scapania, the under lobe is the larger and the plants look as 

 if there were four rows of leaves. The lower lobe is often called 

 the lobule and the upper simply the lobe. Very many species 

 have a third row of leaves on the under side of the stem called 

 technically " amphigastria " or under leaves ; these vary in size 

 from one-third the size of the ordinary leaves to so minute 

 that high powers of the compound microscope are needed 

 to see them clearly. The upper margin of the leaves 

 may overlap the lower margins of the leaves next 

 above as in Porella, or the upper margin of a leaf may lie 

 under the lower margin of the leaf next above as in Plagiochila. 

 In the former case the leaves are said to be incubous, in the latter 

 succubous. As this distinction is in most cases easy to observe, 

 it is given a prominent part in the key. Occasionally the leaves 

 are so far apart that it is hard to determine the leaf arrangement, 



FIGURE 93. Riccardia 

 pinguis (After Sullivant). 

 Portions of male and female 

 plants; vertical section of 

 the fleshy calyptra; male re- 

 ceptacle cut transversely and 

 showing antheridia; open 

 capsule, spores, and elater. 



