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. tricrenaia he distinguished, 

 in addition to the typical form, the vars. subintegristipvla 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 triangvlare 

 (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. M tiller takes an intermediate position 

 between these extremes. In 1913 he described a "var. implexa 

 (Nees) under Pleurosehisma tricrenatwm (Wahlenb.) Dumort., 2 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 or! icular 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. trierenatum. He admitted, 

 however, that these connecting forms were infrequent, even in Central 

 Europe. Midler's figure of the var. implexa agrees on the whole 

 with Lindenberg and Gottsche's figures of Mastigibryum defle.ru m 

 (3 1 implexum laxius (/. 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 laxa 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 



•Bull. Herb. Boissier II. 8: 851. 1908. 



« Rabenhorst 's Kryptogamen-Flora 6*: 270. /. SO. 1913. 



