240 Alexander W. Evans, 



of M. polymorpha and Schiffner^^ has since followed the same 



course. 



The type material of the last synonym, M. oregonensis, con- 

 sists of a series of male specimens collected on Mount Hood, 

 Oregon, by J. Roll, in 1888. A portion of the type in the Under- 

 wood herbarium has been examined by the writer. In his 

 original account of M. oregonensis, Stephani emphasizes the 

 dentate and spinose appendages of the ventral scales and states 

 that he knows no other Marchantia of temperate regions in 

 which similar appendages occur. Howe^® soon pointed out, how- 

 ever, that the appendages in many European and American 

 specimens of M. polymorpha agreed with those of M. oregonensis 

 and expressed the opinion that the peculiarity emphasized by 

 Stephani had no specific significance. Fig. i, G, drawn from 

 M. oregonensis, fully supports Howe's statements. As a matter 

 of fact the appendages are not deeply enough toothed to be 

 called "spinose" or even "dentate" ; it would be more accurate 

 to describe them as denticulate or crenulate. In his Species 

 Hepaticarum, published the same year as Howe's observations, 

 Stephani^^ still maintains the validity of M. oregonensis. He 

 describes the appendages as variously and remotely dentate-spinose 

 and states that they are composed of small subequal cells. Here 

 again Fig. i, G brings out a slight inaccuracy, by showing that 

 the marginal cells are distinctly smaller than the interior cells. 

 In his critical notes he no longer emphasizes the features of the 

 appendages but calls attention to the cruciate internal openings 

 of the epidermal pores, stating that no other North American 

 species has pores of this character. In the material studied by 

 the writer no pores of a distinctly cruciate type were found; 

 they agreed, rather, with the pores of M. polymorpha forma 

 alpestris, as shown in Fig. 2, D. Since both of the distinctions 

 relied upon by Stephani thus break down there seems to be no 

 reason why M. oregonensis should not be considered a simple 

 synonym of M. polymorpha. 



" Engler & Prantl, Nat. Pflanzenfam. i' : 37. 1893. 

 " Mem. Torrey Club 7 : 62. 1899. 

 ''Bull. Herb. Boissier 7:531. 1899. 



