380] TRANS. ST. LOUIS ACAD. SCIENCE. 23 
Clinton ; at the head of Goat Island,* Niagara, between stones, G. Engel- 
mann; Oneida Lake, J. A. Paine; in Oswego fiver, F. Pursh , probably 
(see p. 353). Massachusetts : Mystic Pond near its lower end, gregarious 
in soft mud in 1 foot of water, also in'other parts of the same pond, and in 
Spot, Spy and Horn ponds, on sandy bottom, all near Boston, W. Boott; 
Harrtmond’s Pond, W. G. Farloiv ; Concord brook, gregarious, on firm 
bottom, H. Manh; Beaver Pond near Beverly, J. L. Russell; Uxbridge, 
in Grafton Pond and several other ponds, I. W. Robbins. Vermont: Mt. 
Mansfield, in the Lake of the' Clouds, C. G. Pringle , H. Mann , on gravelly 
bottoms, 1 to 2 feet deep ; Lake Dunmore, A. W. Chapman. New Hamp¬ 
shire : Lake Winnipiseogee, in mud with Gratiola aurea, Eriocaulon , etc., 
G. Engelmann (these specimens were the types of Durieu’s /. Braunii}, 
H. Mann , W. Boott; Echo Lake in the Franconia Mountains (where Mr. 
Tuckerman and myself had found I. lacustris ), TV- Boott. Maine : Moose 
Lake on Kennebunk river, C. E. Smith. Nova Scotia, Shelburne, T. P. 
James. Greenland, in the south, “ Tessermint,” I. Vahl (perhaps this is 
the true I. echinospora ; I could not well analyze the small and poor spe¬ 
cimen in my possession^. Westward the species has been found in West¬ 
ern Canada (Ontario) near Hastings and in a lake northeast of Belleville, 
on a muddy bottom,. J. Macoun. ! Michigan : Bellisle in Detroit river, H. 
Gillman. Utah : Lake at the head of Bear river in the Uintah Mountains,, 
at 9,500 feet alt., 6*. Watson ; this is the rpost western and highest, quite 
isolated, locality known to me. 
This form is most closely connected with the European type; the leaver 
are perhaps not quite so finely tapering; stomata can always be found, at 
least near the tip of the leaf; the sporangia, white in the type, are spotted 
with brown sclerenchym cells; the macrospores I cannot distinguish either 
in size or sculpture; the microspores I find a little smaller. I may state 
hefe that the name of /. Braunii is preoccupied, as it has already been 
given to one of the two species of the Tertiary deposits, the well marked 
spores of which have, been discovered in the German Brown Coal strata; 
Prof. Braun therefore proposed for our plant, if it should eventually be 
considered distinct, the name of I. ambigua „ 
Var. robusta, Engelm., similar to the last, but much stouter, with 25 to 
70 leaves, 5 to 8 inches long, with abundant stomata all over their surface; 
velum covering about one-half of the large, spotted sporangium; macro¬ 
spores 0.36 to 0.55 mm. thick, with the sculpture of the last; microspores 
the same as in last. 
In Lake Champlain, on the north end of Isle La Motte, on a firm sandy 
soil with silt, in 1 to 2 feet of water, C. G. Pringle. Larger and stouter 
than any form of the last, but principally distinguished from it by the abun¬ 
dance of stomata. 
■ Var. Boottii, Engelm. 1 . c. Leaves erect, soft, bright green, fewer (12 
to 20) short (4to 5 inches long) ; stomata, mostly few, near the tip; spo¬ 
rangia nearly orbicular, pale-spotted, f or more covered by the broad 
velum; macrospores 0.39 to 0.50 mm. thick, with longer and slenderer 
0 1 2 3 4 5 6 7 8 9 10 M.ssoo 
Botanic 
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