in the U. S. National Herbarium, in the herbaria of the Missouri 

 Botanical Garden and the University of Minnesota. 



ii. I. DODGEI A. A. Eaton. 



Plants medium to large : leaves 10-75, the submersed spirally 

 ascending, 2o-45cm. long, the emersed io-2ocm. long, often, espe- 

 cially when the plants are not crowded, tortuous and interlaced, 

 2-3mm. broad : velum one-fifth to one-fourth indusiate ; sporangium 

 spotted ; macrospores 500-675 /*, averaging 560 p, with mostly scat- 

 tered groups of irregular, spinulose-rosulate crests ; microspores 

 ashy, 22-40 /u, wrinkled. 



Abundant on the banks of Powow river where overflowed 

 for the purpose of forming a pond during the greater part of the 

 winter, at Kingston, N. H., the only known New England locality. 



12. I. ENGELMANNI A. Br. 



Leaves 15-100, bright green, usually erect except when grow- 

 ing out of water in bare places, stomata abundant : sporangium un- 

 spotted, velum narrow ; macrospores chalk-white, 350-550 /</, honey- 

 comb-reticulated ; microspores 24-29 fi, smooth. 



Very common in clayey soil in ponds and ditches, rarely in 

 mud or sand. For the greater part of the season it is likely to be 

 obscured by a tangle of swamp grasses and other vegetation. 



The spores are peculiar, those of no other American species 

 approaching them in sculpture. Those of Tuckermani, riparia, 

 hieroglyphica, and Harveyi are, it is true, more or less honey- 

 combed for a part of the surface, but the pattern is always incom- 

 plete. The nearest approach to it is Japonica, in which the spores 

 are marked almost identically, but the crests are shorter and less 

 delicate, and the reticulations larger, as well as the spores. 



In Duriaei of Europe the pattern is also the same, but the walls 

 are ridges rather than laminae, and the spores double the diameter. 

 In Azorica the spores are similar in size, but the reticulations are 

 less regular, the walls low, and there is little of the honeycomb. 

 The only othej species with spores of this pattern, is Schweinfurthii 

 from equatorial Africa. My specimens of this species are immature, 

 but one spore would pass for Azorica, while another is covered 

 with short, blunt, crowded tubercles or ridges. The latter was 

 taken from the roots, and may be intrusive. 



In specimens from farther south the spores have a tendency to 

 lose their characteristic form, and the species breaks up into vari- 



