1921] HAUPT—REBOULIA 73 
use of the terms ‘“‘rays” and ‘‘lobes” as applied to the female 
receptacle of the Marchantiales, as follows: 
Nous appellerons donc les rayons les divisions du capitule qui protégent 
les cavités piliféres, et nous réserverons le nom de lobes aux parties du capi- 
tule, qui recouvrent et protegent les involucres. 
According to their interpretation and statements, neither rays 
nor lobes occur in Clevea, Sauteria, and Peltolepis; in some species 
of Marchantia and in all of the other genera of the order lobes only 
occur, while in most species of Marchantia true rays areformed. In 
Preissia both rays and lobes occur, but the rays are reduced, and 
the lobes very indistinct. 
Summary 
1. Reboulia comprises a single polymorphic species, R. hemi- 
Sphaerica, belonging to the Operculatae division of the subfamily 
Marchantioideae. 
2. The thallus bears smooth and pegged rhizoids and 2-ranked 
ventral scales without appendages. The body is differentiated 
into a dorsal and ventral region, and grows by means of a single 
cuneate apical cell. 
3. Air chambers are abundantly formed and develop by cen- 
tripetal splittings. Secondary partitions separate the primary air 
chambers. No chlorophyllose filaments are formed. 
4. Barrel-shaped air pores are developed on the female recep- 
tacle. Those of the thallus and male receptacle are made up of a 
single layer of concentric cells. 
5. Reboulia is monoecious (autoicous). The antheridial recep- 
tacle is sessile, and several may be produced during the growing 
season, but the formation of the archegonial receptacle terminates 
apical growth of the thallus and represents a definite branch system, 
as among the higher members of the order. 
6. The antheridia develop like those of the other Marchantiales. 
7. In the development of the archegonium the 3 vertical walls 
follow the appearance of a transverse wall in the initial cell, and 
further development is typical. Eighteen to 20 neck canal cells 
are formed, but only 4 are present at the time of division of the 
ventral cell. 
