54 FRESH-WATER ALG^E OF THE UNITED STATES. 



darker olive brown, nearly black, attached by a discoid 

 prothallus, caespitose, rigid, curved, cylindrical with wavy 

 outline, sublinear, apex obtuse ; at base thin and nearly 

 colorless; irregularly somewhat swollen, or irregularly 

 nodose. The outer wall thick, opaque ; within hollow with 

 an axillary nodose cord composed of numerous simple fila- 

 ments, usually 40-50, but sometimes 100-150 ; at regular 

 intervals are horizontal branchlets supporting the column 

 in position and bearing 10-15 or more spherical spores. 



Filaments 600-750 // diameter ; internal threads 7-10 yw ; 

 spores 20-25 //. 



Attached to stones in shallow sluggish river water, Beth- 

 lehem, Pa. Frequent 1876-1878. In consequence of artificial 

 changes in the river the latter year, the plant disappeared. 

 Have preserved specimens in Rabenhorst's Algae Exsiccates, 

 No. 2538, and in my own herbarium. This plant is evi- 

 dently closely related to the preceding of which we utterly 

 failed to obtain a specimen, in our oft-repeated efforts ; but 

 while it has much in common it can not be the same, being 

 not in the least branched. 



Plate LXVI, fig. 2, a plant nearly twice the natural size ; 

 fig. 3, a portion of a filament magnified about 40 diameters, 

 walls broken and in part removed to show the axillary cord ; 

 figs. 4, 5, 6, are the supporting threads of the nodes and 

 the spores lodged in them ; figs. 7 and 8, an axillary cord 

 entirely drawn out of the filament. 



Conviction after frequent observation induced the change 

 of the family of the one, and of the genus of the other of 

 these two species. There appears to be no doubt they are 

 both nearly related to the Lemaneacece. 



Family ILPORPHYEACE^E. - 



Thallus mucous, membranaceous or filamentous, formed from 

 a single stratum of cells, most frequently purplish. Vegetation 

 by division of cells in two or more directions. Propagation by 

 tetraspores. 



Genus 3, BANGIA, Lyngb. 



Thallus filamentous, terete or flattened, nearly plane, simple 

 or branched, usually purple, lubricose, formed from a single 

 series of cells. Cell -membrane thick, colorless, sometimes 

 lamellose. Multiplication by the repeated division of the cell- 

 contents in all directions. 



