1923] Evans,—Notes on New England Hepaticae,—XVII 81 
perhaps be better referred to B. tricrenata. In connection with the 
Italian specimens of his forma densior he emphasized the fact that 
the leaves were very caducous and implied that this condition was 
distinctive of B. triangularis. Under B. tricrenata he distinguished, 
in addition to the typical form, the vars. subintegristipula Schiffn., 
cavernarum Schiffn. and pratensis Schiffn., the last two being proposed 
as new. It is unfortunate that he made no attempt to correlate these 
varieties with the subdivisions of Nees von Esenbeck. 
In contrast to the views of Pearson, Macvicar and Schiffner, those 
of Stephani may be cited. In discussing “ Mastigobryum triangulare 
(Schleicher ) "! in 1908, he made no mention of “ Bazzania triangularis 
Pears." but listed both Jungermannia triangularis Schleich., and J. 
tricrenata Wahlenb. as synonyms. He alluded to a wholly etiolated 
forma “implexa” but gave no description of it and even denied its 
varietal rank on the ground that it was merely dwarfed by unfavorable 
environmental conditions. Müller takes an intermediate position 
between these extremes. In 1913 he described a “var. implexa 
(Nees) under Pleuroschisma tricrenatum (Wahlenb.) Dumort.,? citing 
“ Bazzania triangularis Pearson" as a synonym. In this variety he 
emphasized the scarcely convex and distant leaves, that easily be- 
come detached, and the squarrose orbicular underleaves; and he 
stated further that the variety was so distinct that it might at first 
sight be considered a valid species, except for the presence of inter- 
mediate forms connecting it with typical P. tricrenatum. He admitted, 
however, that these connecting forms were infrequent, even in Central 
Europe. Müller's figure of the var. implexa agrees on the whole 
with Lindenberg and Gottsche’s figures of Mastigibryum deflexum 
B 1 implexum laxius (f. 11-13) and represents Schiffner's forma 
densior of B. triangularis, rather than his forma laxa. 
It will be seen from the above citations that European writers are 
still at variance with regard to B. tricrenata, and that those who segre- 
gate off “ B. triangularis Pears.” do so somewhat tentatively. It will 
be seen further that those who do recognize B. triangularis include 
under it not only forms with caducous leaves but also slender forms 
with persistent leaves (the forma laza of Schiffner). In the writer’s 
opinion the presence of caducous leaves is a feature of considerable 
importance from a taxonomic standpoint. Such leaves represent a 
1 Bull. Herb. Boissier II. 8: 851. 1908. 
1 Rabenhorst's Kryptogamen-Flora 62: 270. f. S0. 1913, 
