1916] Evans, — Notes on New England Hepaticae, — XIII 83 



CavcmlLshia plaiyphyUa S. F. Gray, Nat. Ait. British PI. 1: 690. 1821. 

 Madothcca plafyphylJa Dumort. ("omm. Bot. 111. 1822. Porella 

 Notarisii Trevis. Rend. 1st. Lomb. II. 7: 785. 1874. Bellincinia 

 plaiyphyUa O. Kuntze, Rev. Gen. Plant. 833. 1891. [Plate 120.] 



On rocks and trees. Maine: Dover (./. F. Collins 1685); Vassal- 

 boro {E. B. Chamberlain 966). Vermont: St owe {E. G. Britton); 

 Willoughby {E. Faxon; A. Lorcnz & A. W. E.); Jamaica (F. Dobbin). 

 Connecticut: New Haven {D. C. Eafon); Brookfield, Sherman, and 

 New Milford {A. W. E.)\ West Hartford (A. Lorcnz). The following 

 specimens from stations outside New England may likewise be 

 recorded: Bic, Quebec {A. W. E.); Syracuse, New York (L. M. 

 Underwood tt 0. F. Cook, distributed in Hep. Amer. 29); Dresden 

 Station, Adirondack Mountains, New York {C. II. Peck 60) ; Narrows- 

 ville, Pennsylvania (T. P. James); near Yellow Springs, Ohio (TI'. S. 

 Sullivani, distributed in Hep. Bor.-Amer. 9 lb, as Madofhcca rivularis); 

 near Big Bay, Lake Superior region, Wisconsin (L. S. Cheney 5705); 

 Vermilion Lake, Minnesota {Arthur, Bailey d- Ilolway 114a); Vasa, 

 Minnesota [N. L. T. Nelson 5, 945 1:2); Fall Lake, Minnesota 

 (J. M. Holzinger), male plants, doubtful; Iowa City, Iowa {B. Shimek). 

 In Europe the species is exceedingly abundant. 



Although Porella (or Madotheca) plaiyphyUa has long been recog- 

 nized as one of the commonest and most widely distributed of the 

 Hepaticae, questions have arisen from time to time regarding the 

 limitations of the species. By many writers it has been understood 

 in a broad sense, with characters varying within wide limits, the 

 variations, however, l>eing thoroughly unstable and due to environ- 

 mental conditions. By other writers it has been understood in a 

 narrower sense, and one or more closely related species, forming with 

 P. plaiyphyUa a well-defined aggregate, have been distinguished. 

 The difficulties involved were well stated by Nees von Esenbeck.^ 

 In discussing certain Mexican specimens of Madotheca platyphyUoidea, 

 the species most frequently segregated from M. plaiyphyUa, he 

 remarked that they were really intermediate between his earlier 

 conceptions of these two species. And he stated further that two 

 conclusions were possible: either, that M. platyphyUoidea and M. 

 platyphyUa formed a single series of forms (that is, a single species), 

 the extremes being connected by the Mexican specimens; or, that 

 31. platyphyUoidea should be made to include the forms which he had 



' Naturg. der europ. Leberra. 4: 497. 1838. 



