1896.] A New Californian Liverwort. 13 
characters of the sexual organs and sporogonium, but the 
very different structure of the thallus, the similarity of the 
male and female plants, and especially the formation of the 
tubers, make it impossible to unite it with that genus. 
GEOTHALLUS, nov. gen. —Plant thalloid, simple or 
dichotomous by branched, thallus fleshy, wedge-shaped 
or nearly orbicular, partially buried in the earth; margin of 
thallus divided into irregular leaf-like lobes, similar laminz 
upon the dorsal surface; ventral surface with numerous sim- 
surrounded by a sac-shaped envelope: sporogonium globular, 
with very short seta and bulbous foot; capsule-wall composed 
of a single layer of black cells; spores very large, mingled 
with thin-walled sterile cells; plant perennial by means of 
tubers developed at the end of the growing season. 
G. tuberosus, nov. sp.—Plant dioecious, male and female 
alike: spores black, smooth except upon the ventral surface 
where there are reticulate ridges, 120—140y in diameter; 
sterile cells 48—108y in length. 
andy soil near San Diego, California, growing with Ophi- 
oglossum nudicaule. Collected by Mrs. Katherine Brandegee, 
March, April, 1895. 
Stanford University. 
EXPLANATION OF PLATE II. 
Geothallus tuberosus Campbell. 
Figs. 1, 2. Two old plants; 2, seen from above; 4, from the side; 
X 
Fig. 3. A large specimen showing dichotomy; X 4. 
Fig. 4. Secondary shoot from a specimen which had been grown 
under a bell-jar; x 10 
_ Fig. 5. Median section of a fruiting thallus, showing sf, a sporogon- 
lum, 4, the young tuber; X 10 
Fig. 6. a, microtome section of a ripe sporogonium, X 30. 4, mi- 
crotome section of a ripe spore, x 150. ¢, transverse section of the 
Teticulated ridges upon the ventral surface of the spore, X 300. 
ig. 7- An old archegonium, seen in optical section, X 100. 
Fig. 8. a, tetrad of nearly full-grown spores, X 150. 4, two ripe 
Spores, X 150. «¢, three sterile cells, x 150. 
