25 



segment. The second node, usually fertile, carries five or six rays ; the 

 third segments are about 50 in diam., and about half the length of the 

 second ; at times undivided rays spring from the second node (hetero- 

 morpha). The third node bears three or (usually) four terminal rays 

 (occasionally some of these terminals are again divided). The fourth, 

 or terminal, segments (usually four in number) are longer than the pre- 

 ceding, about 40 in diam., and are two-celled. The ultimate cell, a 

 mucro, is slender, 15 to 20 broad at base and 70 to 75 long. 



The plant is monoecious, the oogonia are single at the second and 

 third nodes, rarely on the first node. The antheridium is 130 to 200 

 in diam., often somewhat stipitate; the mature spore varies between 

 175 and 306 long, 204 to 285 broad, reddish brown, with seven strong 

 thin ridges ; the surface marked by reticulae, or rather under high ampli- 

 fication the surface seems to be deeply pitted with irregular pits, while 

 the surface seems uneven ; the margins of the ridges overhang and seem 

 to be "jagged." 



This species varies considerably. Most frequently we find long- 

 leaved forms more slender and with thinner cell-walls, often a monili- 

 form variety, and also more dense and thick-walled forms. Among the 

 latter is one collected by Dr. Rowlee, of Cornell University, in Mud 

 Lake, New York; the stems were 127 thick, the segments of the leaves 

 190, 102 and 88 respectively, and the mucro 30 in diam. at base and 

 41 long. In addition it is freely heteromorphoits, simple undivided 

 rays are borne on every node and extend the entire length of the di- 

 vided leaf; the leaves are at times only once or tivice divided, the 

 oospore 306 long by 285 broad. When the leaves are but once or 

 twice divided one may often find five undivided terminals from the sec- 

 ond node. The long-leaved and "major" forms of this species ap- 

 proach the intermediate species which I** have hesitatingly created 

 between this species and gracilis (trans His). 



In that species, however, the oospore has eight ridges and its surface 

 is smooth, reticulated, or even covered with minute elevations ; the ulti- 

 mate node is also fertile ; the mucro is relatively much stouter and 

 shorter, 20 to 27 broad and 60 to 68 long; still transition forms occur 

 along the way toward gracilis. 



A distinct variety is found in Cuba, Texas and other tropical 

 countries in America, var. compacta A. Br., very low and much 

 branched, forming a thick, turf-like mass. Leaves twice divided. The 

 mucro falls easily, and is usually missing from the older leaves. Nuclei 

 200 to 220 long by 150 or 180 broad. A. Braun also distinguished a 

 forma domingensis of the variety, oospore with six not prominent lines 

 220 long by 200 to 210 broad. In all its forms the surface of the 

 mature oospore is reticulated, the reticulae 4 to 10 in diam. 



