MCALLISTER: MORPHOLOGY OF THALLOCARPUS 119 
Stephani (12), under the name Riccia Curtisit, has elaborated 
the description of Thallocarpus from material ‘‘welche Pastor 
Curtis in seinem Garten gesammelt hat.’ He asserts that the 
plants which he examined were monoecious. In other respects 
his description does not seem to diverge in any important detail 
from that of Austin. He, however, insists that material from 
Austin’s herbarium in the possession of Pearson corresponds fully 
with his description. 
Thallocarpus is of common occurrence in the vicinity of Austin, 
Texas, during late winter and spring, growing most abundantly in 
sandy soil along with Riccias, Sphaerocar pos, and other liverworts. 
The plant studied corresponds very closely with those described by 
Austin if we take into account the essential corrections made in 
his later references to the liverwort. There seems little doubt 
that it should be regarded as the same species. 
Because of the disagreement of Austin and Stephani as to the 
sex of the thallus of Thallocarpus 1 have examined a large number 
of thalli with this point in mind. Although a large number of 
plants of both sexes and of all ages were carefully dissected under 
a binocular microscope I was unable to find both archegonia and 
antheridia on any of the plants examined. Realizing the difficulty 
of detecting and recognizing immature sex organs in dissected 
material I have carefully examined parathn sections of about fifty 
thalli, most of which were female. Part of these plants were sec- 
tioned to obtain material for a study of the morphology of the 
thallus and sporophyte, but special care was taken in each case 
to mount and stain the entire thallus. No case of the monoecious 
condition has been found in this material. The evidence seems 
fairly conclusive that Thallocarpus, as it occurs in the vicinity of 
Austin, is strictly dioecious. 
I have accumulated considerable evi 
four spores of the spore ball of Thallocarpus give rise to two female 
plants and two male plants as has been shown to be the case in 
Sphaerocarpos texanus Aust. (S. californicus Aust.) (13). I shall, 
in the near future, publish my results on this phase of the life 
history of Thallocarpus. 
Material for this study was ¢ 
March, April, and May of the years 1914 an 
dence to show that the 
ollected during the months of 
d 1915. Weak 
