MARCHANTIACEAE. 



451 



2. LUNUIiARIA Adans. 

 Thallus branching dichotomoiisly or innovating at the apex and thus ap- 

 pearing jointed. Air-chambers ^vith distinct boundaries, forming a single layer; 

 green cells in short, simple or branched filaments rising from the tloors of the 

 chambers, each filament two or three cells long; epidermal pores bounded by 

 several concentric rows of cells in a single layer, arranged in distinct radiating 

 series, opening into all the air-chambers. Ventral scales delicate and colorless, 

 divided into a basal portion and an appendage. Antheridial receptacle as in 

 EehouUa. Carpocephalum arising from the extremity of a thallus-branch, 

 composed of a small central portion, from which four tubular bilabiate invo- 

 lucres, each with one or rarely two archegonia (or sporophytes), diverge hori- 

 zontally, the long stalk destitute of rhizoid-furrows; pseudoperianth none. 

 Capsule with a distinct lid, the lower portion splitting irregularly into from 

 four to eight teeth; cells of wall destitute of ring-like thickenings. Gemmae 

 discoid, several cells thick in the middle and with two growing points, borne 

 in crescentic conceptacles. [Latin, lunula, a little moon.] A monotypic 

 genus. 



1. Lunularia cruciata (L.) Dumort. Lu- 

 NULARIA. (Fig. 496.)- Thallus light green, 

 becoming brownish yellow with age, not pig- 

 mented with purple, mostly 2^"-5" wide and 

 V-V long, more or less sinuate along the hya- 

 line margin. Appendages of ventral scales 

 orbicular; inflorescence dioecious; antheridial 

 receptacle terminal on a thallus branch; spores 

 yellowish brown, 15-20 /a in diameter, smooth; 

 elaters usually with two yellowish brown bands 

 of thickening. [Marchantia cruciata L.J 



On earth at base of walls, Hamilton, M. A. 

 Howe. Probably introduced. The species is 

 native to the Mediterranean region but is now 

 naturalized in many parts of the world, especially 

 in gardens and greenhouses. It is rarely fertile 

 but usually produces the characteristic gemmae- 

 conceptacles. 



3. DUMORTIERA Eeinw. Bl. & Nees. 

 Thallus branching dichotomously or innovating at the apex, destitute of 

 air-chambers and epidermal pores. Ventral scales rudimentary and short- 

 lived. Antheridial receptacles oval or circular, terminal on a thallus-branch, 

 surrounded by bristle-like hairs and borne on a very short stalk with two 

 rhizoid-furrows. Carpocephalum arising from the extremity of a thallus- 

 branch, bearing a few scattered bristle-like hairs on the upper surface, convex 

 in the middle and with six to ten blunt lobes, the long stalk with two rhizoid- 

 furrows; archegonia (and sporophytes) borne singly under the lobes, each in 

 a tubular, horizontal involucre extending beyond the lobe and opening by a 

 small apical slit ; pseudoperianth none. Capsule with a distinct lid, the lower 



