— 5— 

 Europe, along the Rhine and its tributaries, in Switzerland and 

 the Pyrenees. In America it is not uncommon. New York State 

 leading with four or five stations in the western and central part, 

 Niagara Falls being the best known. It has also been found in 

 the mountains of Virginia, and in Michigan, Ohio, and Missouri. 

 It occurs at several stations in Ontario, and in the Rocky Moun- 

 tains from British Columbia to Idaho and Montana, and from 

 Washington to California. Its nearest relative seems to be a 

 Mexican species. F. mstgm's Sch. from Mt. Orizaba, of which 

 the fruit is unknown.— £". G. Br it ton. 



ON THE GENUS FISSIDENS, BY ERNEST STANLEY SAL- 

 MON, ANN. OF BOT. 13: J03-I30, PL A TESj-7, 

 MARCH, 1899. 



i L '-pHE structure of the leaf in the genus Fissidens is gener- 

 I ally described as quite anomalous amongst mosses." 

 After describing this structure, the author proceeds to 

 explain the three principal theories which have been advanced to 

 explain the morphology. The first one, accepted up to 1819, held 

 that the leaf corresponds to that of other mosses, and that the 

 sheathing part results from a split in the thickness of the leaf. 

 The second was that of Robert Brown, published in 1819, which 

 held that the double division ot the leaf is its true blade, and the 

 deviation from the normal structure is in the greater compression 

 of the leaf and in the addition of a dorsal and terminal wing. 

 "In support of this view it may be observed that in the lower 

 leaves of the stem both the additional wings are greatly reduced 

 in size, and in some cases entirely wanting, as they are univer- 

 sally in the perigonial leaves, which likewise have the more 

 ordinary form, being only moderately concave and not even 

 navicular." This view was accepted by Bruch and Schimper, 

 and has been followed by Limpricht and others. Lindberg ad- 

 vanced the third theory, and has been followed by Braithwaite, 

 stating that the whole expansion of the leaf is the true leaf, with 

 the exception of one of the wings of the sheathing part, which is 

 considered a stipule. 



In order to prove which of these theories is correct, Mr. Sal- 

 mon has studied the structure of the vein of the leaves of 18 

 species of Fissidetts and those of similar leaves in Bjyo.xiphium, 

 Sorapitla and Diplophyllum, and compared them with leaves of 

 Polytrichitm, Cat liar inea. Pott hi. Bar but a and Tortitla, such of 

 them as have outgrowths or lamelke on their leaves. He con- 



