1923] Evans,—Notes on New England Hepaticae;,—XVII 77 
Hep. Bor.-Amer. $0, distributed as Mastigobryum deflexum, are like- 
wise referable to B. tricrenata; they were collected on “rocks on the 
higher mountains” and probably came from New Hampshire. The 
species is known also from West Ranton, Newfoundland, A. E. 
Waghorne 163, 164, and from Mt. Albert, Gaspé County, Quebec, J r 
A. Allen 27, J. F. Collins 4202 (see Evans, Bryologist 19: 29. 1916), 
but most of the other records from eastern North America were 
based on the next species. 
The wide range of variability exhibited by B. tricrenata has long 
been recognized. Its extreme forms are so different in appearance 
that they would undoubtedly be considered distinct species if they 
were not connected by imperceptible intergradations. In its more 
typical development, as represented by the figures of Macvicar! and 
Müller? the characters are distinct and striking. The plants are 
pigmented with brown, sometimes very deeply so, and grow in com- 
pact mats or scattered among mosses. The individual stems tend 
to be suberect; they give off numerous flagelliform branches from the 
axils of the underleaves and occasional lateral branches of the Frul- 
lania type, the latter forming narrow angles with the stem. The ovate- 
triangular and persistent leaves are approximate or imbricate and 
are strongly convex, when seen from above; the dorsal base is rounded 
or subauriculate; and the apex shows three sharp teeth separated 
by narrow sinuses, the acroscopie tooth projecting slightly beyond 
the others. The underleaves are distant to approximate and quadrate- 
orbicular in outline; the apex is broad and truncate and shows four 
rounded to acute teeth more or less clearly; while the slightly bulging 
sides are entire or vaguely toothed. Diverging from this type are 
forms in which the leaves are distant, less convex, and acute or 
bidentate; while the underleaves may have only two or three vague 
teeth or be almost entire. It is not unusual, in fact, for a branch of 
a typical plant to exhibit divergent features of one sort or another. 
The most thorough attempt to define and describe the numerous 
varieties and forms of B. tricrenata was made in 1838 by Nees von 
Esenbeck,3 who discussed the species under the name Herpetium 
deflecum. He recognized five subdivisions of the first rank (or 
varieties), giving them the names « tricrenatum, B implexum, 
1 Student's Handb. British Hepatics 317. f. 1-4. 1913. 
2 Rabenhorst's Kryptogamen-Flora 62; f. 76. 79. 1914. 
3 Naturgeschichte der europ. Lebermoose 3: 57-74. 1838. 
