12 



In addition to the localities named we must mention Mobile Bay, at 

 the mouth of the river, from which some sterile fragments have been 

 sent by Mr. Chr. Mohr : it is presumed that they belong to this species, 

 for no other large species belonging to this division is known. This 

 species is to be looked for in our Southern fresh waters; the old 

 station, " Santee Canal," is destroyed by the closing of the canal; 

 Lindheimer's station is to be examined again shortly, we trust. 



Explanation of Plate. Figs. I and 2, plant reduced ; Fig. 3, a section of the 

 fruiting "spike," showing a fertile verticil with young fruit; Fig. 4, a mature leaf- 

 tip; Fig. 5, an oospore ; Fig. 6, a section of the shell of a mature spore (diagram- 

 matic), highly magnified. 



NITELLA CLAVATA (Bertero) A. Br., Char. Aust. Hook. Journ. \, 1849; name 

 only; Chara clavata Bertero, Coll. No. 117; also, Gay, Hist, fisica y politica 

 de chile, par Claudio g., Botanica, tomo sexto p. 551, 1853. N. clavata Kuetz. 

 Tab. phyc. VII. t. Si, 1857. 



This species, first founded on South American specimens, has be- 

 come fully elucidated by means of its many forms, which have been 

 found from Uruguay, Chili, Mexico and California, to British America. 

 It is essentially a Pacific Coast species. 



Stems, usually densely tufted, varying from a few inches to over a 

 foot in length ; the lower portion elongated, while the upper verticils 

 become crowded and densely tufted. 



The verticils consist of two sorts of leaves (see Fig. 2) the one, 3 to 

 6, or even 8 in number, once divided into 3, rarely 5, terminals and 

 bearing, when fertile, fruit; the other sort of "leaves" (consult Part 

 i, p. 23) consists of simple, .undivided leaflets, situated between those 

 of the first sort, not always of the same number. 



The leaves of the upper verticils become fertile and bear an apical 

 antheridium and lateral oogonia, usually three in number. The oospore, 

 from 300 to 470 long and from 300 to 420 broad, is marked by 6 or 7 

 prominent and sharp ridges ; the surface is minutely roughened, gran- 

 ular (in some specimens the roughened surface can be distinguished 

 only by the best lenses, for example, a -^ oil immersion is sometimes 

 required.) Antheridia 300 to 400 in diameter. 



VAR. INFLATA, A. Br., Herb. 1863; N. Pottsii, Seeman in lit., 

 1855 (N. capitata Potts); N. clavata var. Muclleri, Schaffner, in 

 seed. 1856, flor. mex. ined. 



This variety is characterized by the enormously inflated leaves, so 

 that the fertile verticils look like small balls 5 mm. in diameter, the 

 leaflets about 2 mm. long by i^ mm. broad; the supplementary, 

 sterile leaflets are often wanting and the oogonia often stipitate ; the 

 oospore may have eight angles. 



