319 HAUPT—FOSSOMBRONIA 1920] 



were obtained by the writer from the same locality in 191 7, about 

 a month earlier than Dr. Land's material had been collected, and 

 served to illustrate the development of the thallus and the sex 

 organs. The writer found F. cristula in this locality growing in 

 cracks on fine, wet deposits of silt on the bottom of an almost 

 extinct lake. Hill notes that "a favorite place of growth in the 

 Tolleston locality was vertical sides of holes left in the mud by the 

 feet of cattle." In the Dune Park region the plants are associated 

 in great abundance with Drosera longijolia. 



Historical summary 



The earliest detailed study of Fossombronia is that of Leitgeb 

 (7), who investigated F. pusilla, a European species. The author 

 made a very careful study of the origin and insertion of the leaves 

 and the development of the stem axis and mucilage hairs in the 

 region of the growing point of the thallus. The apical cell is 

 dolabrate, cutting off alternately right and left segments only. 

 The plants are mostly monoecious, and on those in which antheridia 

 are in greatest abundance, archegonia also occur to a limited 

 extent. In regard to the order of appearance of the sex organs, 

 the author says: "Aber ich fand haufig Sprosse mit vollig ent- 

 wickelten Kapseln, welche nach der Spitze hinwieder reichlich 

 Antheridien producierten." The position of the antheridia and 

 archegonia is the same as that of the other species, and both 

 originate close to the apical cell. In regard to the development 

 of the antheridia it is stated that they deviate in no way from the 

 normal type, although no figures are shown to illustrate this develop- 

 ment. The venter of the archegonium is 2 cells thick before 

 fertilization. 



The fertilized egg is elongated in the direction of the arche- 

 gonium axis, and divides by 2 horizontal walls, forming a tier of 3 

 superimposed cells, of which the lower forms the foot, the middle 

 cell the seta, and the upper one the capsule. The upper and lower 

 cells divide more actively than the middle one. The differentiation 

 of wall cells and sporogenous tissue in the capsular region occurs 

 early. The mature capsule is 2 -layered; the inner wall forms 

 annular thickenings. At the apex the capsule wall is 3-layered. 



