Evans: NOTES ON GENUS HERBERTA 205 
Lindb.; in this species, according to Andreas, the wall is composed 
of seven or eight layers and has a thickness of 1304. In all 
these forms he describes local thickenings in the cells of all the 
layers. In the innermost layers the thickenings are in the form 
of half rings extending across the inner tangential wall (see TEXT 
FIG. 10) In the other layers they are in the form of bands on the 
radial walls. Even here, however, the bands sometimes extend 
to a greater or less extent along the tangential walls. According to 
Andreas the structure of the capsule wall in the leafy Hepaticae 
shows comparatively little variation, and the genus Herberta 
agrees on the whole with his account. It might be added that 
the valves are covered on the outside by a granular wax-like de- 
posit, and that secondary splits sometimes occur in one or more 
of the four primary valves. 
Many years ago Spruce* described the occurrence of rudimen- 
tary shoots on the leaves of Herberta. According to his account 
they arise singly or in pairs from the cells of the vitta in the basal 
portion of the leaves and never in the divisions. These shoots 
have not been observed by the writer and are probably developed 
under exceptional conditions. They represent the only type of 
vegetative reproduction known in the genus. As Spruce’s figures 
clearly show, the shoots bear three ranks of small bifid leaves and 
show no signs of dorsiventrality. They resemble in many 
respects the adventive shoots borne on the leaves of certain species 
of Plagiochila, although they are much less abundantly produced. 
REVISION OF THE SPECIES KNOWN FROM EuropPE, CANADA AND 
THE UNITED STATES 
According to most recent writers on the Hepaticae the genus 
Herberta is represented in Europe by only two species. The first 
of these is H. adunca (Dicks.) S. F. Gray, the type of the genus; 
the second, H. Sendtneri (Nees), sometimes known as H. séra- 
minea (Dumort.) Trevis. The range of H. adunca, according to 
‘ 
available records, is restricted to Norway, the Faroe Islands and 
i is even more circum- 
the British Isles; the range of 1. Sendtner 
scribed, being accredited only to the Austrian and Bavarian Alps. 
the branch-bearing leaves of Jungermannia juniperina, Sw. Phytologist 2: 
* On 
85, 86. 1844. [lIllust.] 
