A Monograph of the Genus Akma. 2.3 



formed sporophylls are distantly disposed, but the later- formed, 

 normal-sized ones are more approximate. They are alternate in 

 some species and nearly opposite in others. But such arrangement 

 can be discriminated only in the early -formed sporophylls, as the 

 middle and upper ones are generally quite close together. In all 

 species, new sporophylls appear successively above the older ones 

 as the stipe increases in its length at the transition point. The 

 lov7er older ones drop off one after the other leaving verrucose 

 scars on the edges of the stipe. In some species, however, the 

 growth in lengtli of tlie stipe ceases before long, and the sporo- 

 phylls are condensed to a limited point. A noteworthy example 

 of such is seen in A. angusta. In it the sporophylls, except a few 

 early-formed ones, grow fasciculately from a point in an upper 

 part of the stipe, the point being much broader and more com- 

 pressed than the naked portion (Plate XV, fig. 1). 



The sort cover the greater parts of both surfaces of a sporo- 

 phyll, leaving always a narrow border along the margin and 

 frequently a sterile membranous portion on the upper end. 



After having examined a considerable number of specimens of 

 Alarm, the present writer has come to the conclusion that one is 

 not justified in determining the species of Alaria, except in a few 

 cases, unless a specimen with fully matured sporophylls is before 

 him. The other parts of the frond serve of course to help the 

 determination but should never be used alone. Sterile specimens 

 of A/ar/a from the North Pacific where various species occur 

 simultaneously at the same place, are seldom determinable with 

 certainty. 



The value of sporophylls as a specific distinction of Alaria lies 

 in two points : a) their general shape and texture ; b) their dis- 

 position on the stipe. 



