1916] Evans,— Notes on New England Hepaticae,— XIII 107 



strongly although its relationships with P. platyphylla are perhaps 

 closer. The stems are pinnate or sparingly hipinnate, and the shoot- 

 system on account of the regularity of the branching may assume a 

 fern-like form. This, however, is always less marked than in typical 

 specimens of P. platyphylla, and in some cases, especially in drier situ- 

 ations, the branching may be very irregular. 



The lobes, lobules, and underleaves differ from those of P. pinnata 

 in being usually more or less dentate. The dentation, in fact, although 

 not to be compared with that of the European P. laevigata (Schrad.) 

 Lindb. in its typical forms, is commonly more marked than in P. 

 platyphylla and its immediate allies, and often helps in determining 

 sterile specimens of M. Cordaeana. Taking up the lobes (of the stem- 

 leaves) more in detail they are found to be ovate and rounded at the 

 apex, much as in P. platyphylla. In some cases they are not attached 

 to the lobule at all, no keel being present. In other cases an ex- 

 tremely short keel can be demonstrated. Whether a keel is developed 

 or not the lobe is usually distinctly dilated at the carinal base (as it 

 may be called) and may therefore be described as cordate; at the 

 dorsal base the cordate condition is much less frequent, the lobe in 

 most cases gradually narrowing into a short decurrent portion. The 

 teeth of the lobe are much like those of P. platyphylla but tend to be 

 sharper, more distinct and more numerous. 



The lobules afford some of the most distinctive characters of the 

 species. They are usually much smaller than in /'. platyphylla and are 

 ovate to lanceolate in form, the apex varying from obtusely pointed 

 to acute.. On branch-leaves the apices may even be acuminate. The 

 margins of the lobules are often irregularly revolute in places, the 

 whole lobule being thus variously contorted or crispate. The line of 

 attachment is sharply arched ami the inner edge is usually twice or 

 three times as long as the outer, so that the deeurrenee is very evident. 

 Sometimes, when no keel is present, the outer edge extends farther 

 backward than the lobe in the form of a narrow wing, but this is never 

 so long as the inner edge. Marginal teeth or cilia are restricted for 

 the most part to the decurrent portions. They are exceedingly vari- 

 able in number, in form, and in size, but are usually more in evidence 

 than in the lobules of P. platyphylla. 



The leaf-cells average about 30 jjl in the middle of the lobe and are 

 therefore a trifle larger than in typical forms of P. platyphylla and con- 

 siderably larger than in P. pinnata. They have thin walls and small 



