38 
ameter with thin, jagged crests, sometimes anastomosing, espec- 
ially on the lower surface ; commissural ridges cristate ; micro- 
spores tuberculated, 26-32 ji. 
This species may be distinguished from I. lacustris, which it 
somewhat resembles, by the crested ridges of its macrospores, 
which often form reticulations on the lower side of the spore ; by 
the presence of stomata on the leaves ; a spotted sporangium with 
a wider velum, and also as shown by Mr. T. Chalkley Palmer, by 
its being polygamous — Botanical Gazette , Apr. 1896. 
Type locality, banks of the Delaware river near Philadelphia, 
Nuttall; Wm. S. Zantzinger. Uxbridge, Mass., J. W. Robbins. Brat- 
tleboro, Vt., C. C. Frost. Lake Saltonstall, Ct., Setchell Amherst 
Catalogue, Tuckerman. Banks of the Powow river, East Kingston, 
N. H., and in the Merrimac at Newburyport, Mass., R. D. 
This species when living as is often the case in the mud on 
the tidal tracts of rivers, when near high water mark; is commonly 
small, with leaves two or three inches long, but when submerged 
for a greater portion of the time the plants become larger. 
[The description of the species next following is contributed 
by Mr. A. A. Eaton.] 
I. foveolata A. A. Eaton, n. sp. Plant amphibous ; trunk 
bilobed, rarely trilobed, inch in diameter ; vernal leaves not 
seen estival 15-70, very stout, 2-6 inches long, pink even when dry, 
or rarely dark green ; stomata few, near thetips only ; peripheral 
bast-bundles absent ; diameter of the assembled sporangia often 
1^ inches ; many plants containing only macrospores ; velum one- 
fifth to one-third indusiate ; ligule round-ovate, little exserted ; 
sporangia thickly sprinkled with very dark cells, these sometimes 
collected in groups ; macrospores 380-560 /j, average 440 g, tetra- 
hedro-globose with a thick integument (54 p), covered beneath 
with very thick-walled reticulations so that the openings appear 
like little pits, (whence the name) ; above, the reticulations are 
elongated, especially next the commissures, or the walls even par- 
allel anastomosing, or in isolated groups ; microspores dark brown, 
