170 MINNESOTA BOTANICAL STUDIES. 



The plant is large and is characterized by comparatively long 

 internodes (1-2 cm.) and by the smooth calcareous crust which is 

 interrupted by an uncalcified area at each node. The dichotomy of 

 the frond is remarkably regular with no lateral proliferations and 

 all parts of the frond are very uniform in diameter, only the basal 

 trunks being enlarged. These characters give the plant a loosely 

 fascicled segmented aspect. The frond, even when decalcified, is 

 firm and almost cartilaginous. 



The central cylinder consists at first of filaments about 15-20 

 mic. in diameter. The axis becomes much thickened in older parts 

 of the plant by the numerous smaller filaments w^hich originate from 

 the lower cells of the cortical branchlets and grow along and into 

 the central cylinder. 



The proximal cells of the cortical branchlets are cylindrical, 

 8-11 mic. in diameter and 6-8 times as long. The same form of 

 cell occurs above with slight decrease in diameter, the upper 3-5 

 cells being obovate (averaging 7x11 mic.) and forming the abrupt 

 corymbose tips, the distal cells about one-half as large as the others. 

 Only one or two cells occur intermediate in form between the elon- 

 gated and oval cells. The lower cells bear lateral rhizoid-like fila- 

 ments which form the smaller filaments of the central cylinder. In 

 antheridial material the distal 1-2 cells of nearly all the cortical 

 filaments bear groups of sperm-bearing filaments, the sperm cells 

 themselves being 2-3 mic. in diameter. This appears to be a very 

 distinct species. 



Section II. Corymbosae sect. nov. 



The following two species belong to the group represented in 

 Agardh's revision by L. corymhosa alone. They stand in a some- 

 what intermediate position between his sub-genera. With the out- 

 ward appearaance of L. cheyneana and the same medullary struc- 

 ture as is found in that species, they possess cortical branchlets re- 

 sembling those of L. leprosa. It seems that they should be placed 

 together in a section intermediate between Agardh's Eii-Liagora 

 and Goralia and this section may well be termed Corymbosae from 

 the typical species. As is indicated below, the first species of my 

 collection appears to correspond most closely to Agardh's L. corym- 

 bosa, but I have been unable to compare my specimens with an} 

 herbarium material of that species and from the description of 

 L. corymbosa it is possible that the material upon which that species 



