68 METZGERIACEAE 
4 Antheridial involucre, Х 23. 
5 and 6. Opposite faces of a single spore, Х 305 (the former is thought to be 
what was originally the outer face, chiefly because the ridges are here a little the 
stronger The number of completely closed meshes in the latter is unusual y great). 
7 and 8. Spores, Ж 305, the latter showing the flattening. ` 
12. GEOTHALLUS Campb. Bot. Gaz. 21: 13. A. 2. 1896. 
Ann. Bot. 10: 489. pl. 24, 25. 1806. 
Gametophore transitional in character between the thalloid and 
foliose types of Hepaticae, consisting of a simple or dichotomous 
mostly unistratose leaf-like expansions and often bearing smaller 
irregularly disposed leaf-like laminae on the dorsal surface ; cells 
large, thin-walled ; root-hairs numerous, long, colorless. Dioicous. 
С and 9 plants similar, or the former slightly smaller. Sexual 
organs usually few, often standing near the axils of the leaf-like 
lobes, enclosed, in most cases singly, by unistratose involucres. 
shaped, becoming saccate or campanulate at maturity of the 
sporogonium, the orifice large. Calyptra mostly of two layers of 
cells, ruptured rather late, the upper part, with the archegonium- 
neck, persisting on the apex of the capsule : 
Sporogonium consisting of a nearly spherical indehiscent cap- 
sule, a very short seta, and a bulbous foot. Capsule wall of a 
single layer of large, dark-colored cells, without annular or other 
local thickenings, Spores separate at maturity, very large, thick- 
walled, the inner face reticulate, otherwise smooth, accompanied by 
oval or ellipsoidal-cylindric, thin-walled, sterile cells. 
I. GEOTHALLUS TUBEROSUS Campb. / с. 
Plant sim 
wide, perennial through the conversion of a large portion of its 
axis Into an oval or flattened tuber: leaf-like lobes nearly hori- 
zontal or somewhat ascendirig, extremely variable in form, mostly 
oblong, obovate, or linear-ligulate, 1.5-2 mm. in length, rarely 
broader than long, sometimes cristate-laminate at base, the таг- 
ез of g over 200 и in length: 4 invo- 
lucre .45 mm, in height : capsule .8 mm. in diameter, seta about 
