24 



NITELLA TRANSILIS, sp. nov. (N. tenuissima var. lo?igifolia Allen, 

 in Characeae Exsiccatae Americanae. ) 



Plants simple, tufted, 5 to 10 cm. high, rarely branched. Stem 

 slender 125-130 in diam. Verticils about 8 mm. distant (in central 

 portions of stem), not becoming condensed above. Leaves 6-7 mm. 

 long (the verticils rarely overlapping, even at apex of stem). Verticils 

 consist of five or six leaves. Leaf, first segment 80-100 in diam; first 

 node sterile, of six divisions; second segment 50 to 60 in diam.; 

 second node fertile, bearing six divisions ; third segment 40-50 in 

 diam.; third node, often fertile, bears 3-4 terminals, terminals not 3- 

 celled like gracilis, 40-50 in diam.; mucro 20 in diam. at base, 60-70 

 long. 



Oogonia isolated at second (rarely at third) node of the leaf. 

 Oospore 272 long with j8 somewhat prominent striae (varies 2 7 2 to 

 285 long, 245 to 265 broad, with 8 striae). The Nordstedt markings 

 on the spore membrane vary. In specimens collected by John Robinson 

 in " Chebacco Pond," Mass., the spore membrane is perfectly smooth; 

 from Sparta Pond, New Jersey, T. F. Allen, mature oospores show 

 minute points, almost conical, on the outer membrane, while the 

 middle membrane is reticulated. In specimens from Rhode Island, T. 

 F. Allen, the mature oospore membrane is reticulated. In some features 

 it seems to approach the rare N. confervacea Breb., from Normandy 

 (which I have not been able to obtain). From N. gracilis it differs by 

 the presence of fruit on the second node of the leaf, never on the first 

 {confervacea is said to be fertile at the first node), by the simple char- 

 acter of the terminals and by the Nordstedt markings. From tenuissima 

 similar differences distinguish it, though it seems to approach this more 

 closely than gracilis. 



NITELLA TENUISSIMA (Desv.) Coss. et Germ. 



Plants very small, rarely more than a few inches high. Stems 

 tufted, two to five from a single root. The very slender stems, 140 to 

 250 in diameter, spread widely, often reclining close to the ground. 

 The stems bear six to eight whorls of leaves, which are remote in com- 

 parison with the length of the leaves, and usually are short and quite 

 dense, rarely reaching over more than a third of the internode ; in some 

 forms the whorls of leaves are so short that the stems appear moniliform. 

 The verticils consist of six leaves which are three or rarely four times 

 divided. The first segment is rarely over 75 in diameter, with quite 

 thick cell-walls, and about one-third the length of the entire leaf. The 

 first node (usually sterile) carries six or seven rays; the second seg- 

 ments, about 50 in diam., a little more than half the length of the first 



