342 



Dansk Botanisk Arkiv, Bd. 3. Nr. 1. 



dense tufts. Its flat, leaflike thallus is thin, consisting, with the ex- 

 ception of the midrib, of only a single layer of cells; it is repeatedly 

 forked and narrowed at each ramification, the internodes, on account 

 of this narrowing, being lanceolate. One of the flat sides of the 

 thallus is turned upwards, the other downwards against the sub- 

 stratum. From the side turned down rhizoids are issued at the fork- 

 ings of the thallus (Fig. 338). Small epidermal cells are cut ofl" from 

 a group of central cells at the forkings, cp. Nägeli, 1855, 1. c, p. 73, 

 pi. VIII, figs. 1 and 7. From these cells a bundle of rhizoids grow 



Fig. 338. Caloglossa Leprieurii (Mont.) J. 

 Part of a plant. (About 6:1). 



Ag. 



out, cohering more or less at their outgrowth, later on separating 

 and spreading out in all directions. By means of these haptera the 

 plant is fixed to the substratum. 



I have not come across tetrasporangia in my material, but tetra- 

 sporic plants and the structure of the tetrasporangia have been de- 

 scribed by Cramer, 1. c. The tetrasporangia are formed in great 

 number in a single layer in the tissue on both sides of the midrib. 

 In the part of the thallus destined to produce the tetrasporangia 

 the cell-division takes place in a way somewhat diflering from that 

 in the vegetative thallus. The primary marginal cells form only a 

 single row of cells; these cells are later divided into two cells: one 

 above, namely the mother cell of the tetrasporangia, and one below 



