EVANS—THE NORTH AMERICAN SPECIES OF ASTERELLA. 259 
shows two spirals, while the ends show only one. Considerable varia- 
tion in both length and diameter is to be expected. 
SYSTEMATIC TREATMENT. 
The subdivisions of the genus which have been proposed have not 
been very widely accepted. In the Synopsis Hepaticarum two sub- 
genera of Fimbriaria are recognized. In the first, to which no special 
name is assigned, are placed the “species genuinae,” characterized by 
a pseudoperianth which definitely surpasses the involucre; in the 
second, called Brachyblepharis, the pseudoperianth is said to be but 
little longer than the involucre, and the latter is described as being 
remote from the margin of the receptacle. The first subgenus is 
further divided into two sections, the first with pendent pseudo- 
perianths, the second with horizontally spreading pseudoperianths. 
Many years later Stephani’ proposed a division into two groups 
(or sections), based on the structure of the thallus. In the first 
group, Spongiosae, the thallus is said to be comparable to that of 
Ricciella; in the second group, Jfarchantioides, it is said to have 
chlorophyllose filaments. 
Schiffner? combined both classifications under the generic name 
Hypenantron, To his first group, the equivalent of the first subgenus 
of the Synopsis, he gave the name Luhypenantron and retained the 
name Brachyblepharis for the second. He regarded the groups as 
sectional in value, however, rather than as subgeneric. Under the first 
section he included Stephani’s two groups. 
In Stephani’s monograph of 1899 these attempts at classification 
are ignored and a new classification, based primarily on the form 
of the female receptacle, is proposed. Four subdivisions are recog- 
nized. In the first the receptacles are described as disciform; in the 
second, as hemispherical in the center; in the third, as distinctly 
conical; in the fourth, as highly umbonate. Under each of these 
subdivisions (except the last) subordinate groups are recognized, 
based on differences in the appendages of the ventral scales. 
Although many of the distinctions thus noted are often helpful 
in separating species, some of them at least are based on vague and 
inconstant characters, and the writer feels that they are hardly suffi- 
cient to characterize subgenera or even sections. This view seems to 
have been held by Howe, who made no attempt to divide the genus 
into subordinate groups, and Miiller also, in his treatment of the 
European species, leaves the genus intact. 
In the preparation of this paper the writer has had the privilege 
of examining the specimens in several herbaria and would express 
*Hedwigia 31: 122, 1892. 
? Engl. & Prantl. Pflanzenfam. 1°; 34. 1898. 
