106 H. N. DIXON AND W. E. NICHOLSON. 



American continents, and it transpires that it was the original of 

 the H. atrovirens Dicks., and the plants usually passing as 

 Ps. atrovirens among European Bryologists helong to a quite 

 distinct species (or group of species). Dr. Best therefore follow- 

 ing the law of 'specific' priority retains the name of P. atrovi- 

 rens for the plant to which Lindberg gave the name patens; 

 but the accuracy may be questioned of citing the figure in the 

 Bry. Eur. as the authority for the name „Pseudoleskea atrovi- 

 rens (Dicks) Bryol. Eur. 5: 2. pi. 477, 1852". It appears evident 

 that some at least of the figures there given (e. g. 1,3) do not 

 represent Dickson's type, i. e., Ps. patens Limpr,, and that the 

 citation should at least be limited by „pro par te^^. However 

 that may be, the limits of the original H. atrovirens Dickson 

 (Ps. patens Limpr.) are clearly enough defined and easily under- 

 stood. This species however represents but a small proportion 

 of the European & American plants that have until recently 

 passed under the name of P. atrovirens, and the more difficult 

 task arises how to deal with the remainder. The most usual 

 European form, such as that found on Ben Lawers and other 

 Scotch mountains in company with Ps. patens Limpr. and more 

 frequently in Scandinavia & other continental countries, has not 

 been found (in its typical form at least) in North America, and 

 it has not therefore, unfortunately for us, fallen to the lot of Dr. 

 Best to investigate this plant fully, nor to point out the distinc- 

 tions between it and others of the group with the same minu- 

 teness that he has applied to the description of the North 

 American forms. He suggests however that an examination of 

 the type of Leskea incurvata Hedw. may probably show its 

 identity with the above plant and settle the question of the 

 earliest specific name. 



In addition to this typical or at any rate common plant 

 there are certain forms differing in more or less important 

 points, as to which opinions may vary whether they should hold 

 specific rank, but at any rate forming groups separated off from 



