Ill THE JUNGERMANNIALES 75 



ANACROGYN^ 



Jungermannlales Anacrogynae. Apical cell of female axis 

 never becoming transformed into an archegonium. 



A. Anelatereae. No true elaters, but sterile cells repre- 

 senting these. Capsule cleistocarpous. Four genera, 

 T hallo car pus, Sphcerocarpus, Riella, Gcothallus. 



B. Elatereae. Capsule opening either by four valves or 

 irregularly. Elaters always developed. 



a. Gametophore always dorsiventral, either strictly 

 thallose or with more or less developed leaves. Fam- 

 ilies, — Metzgerieae, Leptothecese, Codoniese. 



b. Gametophore upright with three rows of radially ar- 

 ranged leaves. Fam. I., Haplomitrieae. 



Anelatere^ 



The simplest form belonging here is Sphcerocarpus, a genus 

 that shows certain affinities with the Ricciacese, but on the 

 whole seems to be more properly placed at the bottom of the 

 series of the Jungermannlales. 



Sphcerocarpus terrestris occurs in Europe and the south- 

 eastern United States. In California it is replaced by two 

 species, 6^. Calif orniciis and S. cristatits, which until recently 

 (Howe (3)) were not recognised as distinct, and were con- 

 sidered to be a variety of S. terrestris. They are small plants 

 growing upon the ground, usually in crowded patches, where, 

 if abundant, they are conspicuous by the bright green colour of 

 the female plants. The males are very much smaller, often less 

 than a millimetre in diameter, and purplish in colour, so that 

 they are easily overlooked. The thallus is broad and passes 

 from an indefinite broad midrib into lateral wings but one 

 cell in thickness (Fig. 30). The forward margin is occupied 

 by a number of growing points formed by the rapid dichotomy 

 of the original apex, and separated only by a few rows of cells. 

 From the lower side of the thallus grow numerous rhizoids 

 of the thin-walled form. The whole upper surface is cov- 

 ered with the sexual organs, each of which is surrounded by 

 its own very completely developed envelope. 



A vertical section passing through one of the growing 

 points (Fig. 30, C) shows a structure closely like a similar 

 section of Riccia. The apical cell {x) produces dorsal and 



