118 Rhodora [May 



even if recognized as a valid species, must be regarded as a " kleine 

 Art " in the P. plafyphylla-group. According to our present knowledge 

 the range of the true P. plaiyphyUa is northern rather than southern 

 in North America, but it must be admitted that our knowledge is still 

 incomplete. Perhaps when more is known about the geographical 

 distribution of these two species it may be possible to utilize this 

 knowledge in the determination of doubtful specimens. 



Schiffner's Madothcca Baucri has as yet been reported from Europe 

 only. The writer has not had access to Schiffner's types but has 

 examined a series of authentic specimens including those in Jack, 

 Leiner & Stizenbergcr's Kryptogamen Badens 164, and in Raben- 

 horst's Hepaticae europaeae 5g, both of which arc referred by Miiller 

 to M. Baueri. No. 1(>4 was collected by F. Himmelseher near Salem 

 in BadeQ and No. 52 by A. Rose near Schnepfental in Thuringia. 

 The specimens studied agree closely with the published descriptions 

 but indicate that the validity of .1/. Baucri is fully as doubtful as that 

 of M. platyphylloidca. The characters emphasized by Schiffner are 

 the following: the large size and irregular branching; the broadly 

 elliptical to almost orbicular lobes; the distant, small, almost plane 

 underleaves, broadly rounded at the apex; the large leaf-cells, averag- 

 ing about 36> near the apex of the lobe; the narrow mouth of the 

 perianth with crowded cilia; and the clatcrs with one spiral, except 

 in the median portion where two are present. Miiller describes the 

 cells in the middle of the lobe as 30-35 u in diameter, and adds that 

 one or two blunt teeth are borne on the margin of the lobe, that the 

 lobule is long decurrent and often toothed in the decurrent portion, 

 that the perichaetial bracts are shortly and bluntly denticulate 

 throughout, and that the crowded cilia at the mouth of the perianth 

 are three or four cells long. Aside from the features mentioned 

 M. Baucri is described as being much like P. plaiyphyUa. 



The material studied by the writer brings out the fact that many of 

 the differential characters relied upon are subject to great variation. 

 This is particularly true of those drawn from the form and dentation of 

 t he leaves. The large leaf-cells afford a character which deserves more 

 weight. The difference in size, when these cells are compared with 

 those of P. platyphylla and P. plafyphylloidca, is usually pronounced, 

 although Miiller brings out the fact that in the variety subsquarrom 

 of i/. plaiyphyUa the cells approach those of M. Baucri. In the mout h 

 of the perianth the resemblance to P. platyphylloidca is particularly 



