GEOTHALLUS 69 
92 и long ; spores nearly black, 120-150 и in maximum diameter, 
spore-wall smooth or very minutely punctulate and very thick 
(8-12 и) except as to the comparatively small inner face where it 
is thinner and bears reticulate ridges, the meshes about I5 м in 
width ; sterile cells 48-108 и long. 
On sandy soil, near San Diego (Mrs. Katharine Brandegee ; 
March, April, 1895), associated with Op/roglossum nudicait.c. 
A remarkable plant, clearly allied to Sphaerocarpus, yet as 
clearly distinct from it generically. Living laboratory-grown 
specimens, bearing antheridia and archegonia, and mounted micro- 
tome sections of the mature sporogonium, have been furnished us 
through the generosity of Professor Campbell. Mature % invo- 
lucres we have not seen and our description of these is adopted 
from the author's description with the assistance of his figure 5 
(Bot. Gaz. 1. с.). We have seen the spores only in microtome 
sections, yet it seems certain from these that the spore-surface is _ 
reticulate upon the inner face and otherwise practically smooth, as 
described by Professor Campbell—a unique character, so far as 
our observations upon the Hepaticae go. In Anthoceros, Меса, 
Fossombronia, etc., it is always the outer face of the spore that is 
the more conspicuously roughened. Doubtless the restriction of 
the ridges in Geotha/lus to the inner face is correlated in some way 
with the unusual thickness and rigidity of the spore-wall in the 
region of the outer face, especially as the ridges of the inner face 
are seen in section to be formed by a folding of the exospore, the 
contour of which is followed by the episporic coating. 
The gametophore of Geothallus (as grown in the laboratory) 
much resembles in general appearance that of Fossombronia longi- 
seta, though the “leaves” are stiffer, less crisped, and more ћоп- 
zontal. 
The formation of tubers is a character which this hepatic 
shares with Anthoceros dichotomus Raddi, Anthoceros Donnellii 
Aust, Anthoceros tuberosus Tayl., Anthoceros phymatodes M. А. 
Howe, Riccia vesicata Tayl. (= К. cancellata Tayl. fide Stephani), 
Riccia perennis Steph., Riccia bulbifera Steph., opu 
Preissii Gottsche, Petalophyllum lamellatum (Hook.) Lindb., an 
Fossombronia tuberifera Goebel. The stem of ae 
longiseta also is often more or less tuberously thickened at s | 
apex, especially in specimens from the southern part of Cali- 
