46 



but rarely in salt water. In the United States it seems to be the 

 most common species, being reported everywhere. It grows to a 

 considerable length, with long slender leaves, in running water, or 

 becomes very small and compact in still ponds. Multicellular tubers 

 are formed on the lowest nodes. 



Specimens have been found as follows : Maine, Prof. O. D. Allen» 

 Vermontj at Charlotte (forma micropiild)^ Mr. Pringle ; in Willoughby 

 Lake {tenuior longifolid)^ Messrs. Horsford and Faxon ; at Ferris- 

 burgh, Mr. Faxon. Massachusetts, at Boxford, Messrs. Faxon and 

 T. F. Allen ; at Natick and Cambridge, Mr- Faxon ; at other places 

 by Rev. Mr. Morong. Connecticut, at New Haven, Prof. O. D. 

 Allen ; in Litchfield County quite common, T. F. Allen. New York, 

 at Albany, Mr. Peck; at Penn Yan (forma macroptila var. barbatd) ; 

 in the lakes of Western New York, especially in Hemlock and Honeoye 

 Lakes, and common in the lakes in the Adirondacks, T. F . Allen. 

 Illinois (forma longifolia major^ var. Hedwigii)^ Dr. J. Schenck. 

 Iowa, J. C. Arthur and Prof. Bessey. California, Dr. A. Kellogg 

 (forma macroptila). Yellowstone Park, in the hot Geyser Springs, 

 temperature loo** -^•, finely in fruit, but with only two elongated 

 bracts, the lateral bracts very minute, herb. Gray, collected during 

 Hayden's Survey. 



{Ch, delicatulay Ag., by some considered a variety of Ch. fragilisy 

 grows in Fort Pond, Montauk Point, Long Island. It is incom- 

 pletely triplostichous ; the stem is armed with small spines; the 

 stipules are well developed ; and the bracts are verticillate, but the 

 dorsal ones small. Intermediate forms are known between this 

 species and the typical yr^^/Z/x.) 



Description of Plate xvii, Ck, /w^^mw^jt^t.- A represents the plant, natural size. 



Fig. I, a lower sterile verticil. Fig. 2, a higher verticil with naked leaves and with 

 one node fertile, one quite sterile, and the stem corticated with a disconnected series 

 of primary, node-bearing cortex-tubes. Fig. 3, an upper verticil, showing three (of 

 the seven) leaves, one with a single fertile node, with the lowest internode corti- 

 cated like the stem ; one with two fertile nodes, the lower of which has a perfect 

 double cortex, the upper an imperfect cortex, and one sterile leaf without any node 

 whatever. Fig. 4, a section of the stem showing the relation of the cortex-tubes to 

 each other. Fig. 5, the terminal articulation of a leaf with its short mucrona^e 

 cell. All ihe figures are magnified 100 diameters. 



Explanation of Plate xviii. Ch. crinita. — A represents the normal size of the 

 plant. Fig. i, a portion of the stem with triple spines (less numerous than in nature, 

 when they completely hide the stem); large double stipules equalling the lowest joint 

 of the leaves; the long, verticillate bracts; the short coronula of the sporangium; and. 

 at a, the three bracteoles subtending the sprorangium, (The male plant I have 

 never seen.) Fig. 2, terminal nodes of a leaf, showing the one-celled, naked ter- 

 minal, surrounded by long bracts. Fig. 3, a section of the stem. Fig. 4, a nu- 

 cleus from Montauk Point {Soxm^ pachysperma). Fig. 5, nucleus from Nantucket 

 (forma leptosperma). 



Explanation of Plate xix, Ch. evo/u/a.—Asnid B represent the natural size of 

 the plant; B though small is perfectly mature, with full-sized sporangia. Fig. I. the 

 stem with double spines, double stipules and one leaf with three fertile, two sterile 

 nodes and a two-celled, terminal, naked segment, magnified 30 diameters. Fig. 2, 

 a portion of the stem, showing at a, ^, and c the partial development of one cell of 

 a cortex-node mto a cortex-tube, magnified 30 diameters. Fig. 3, a section of the 



S 



the site of the antheridium ; at d, b, the central cortex-tube, in the lower node cov- 



