2^8 TRANS. ST. LOUIS ACAD. SCIENCE. 



tapering to a fine point, with very short, often almost square, epidermis 

 cells; orbicular sporangium not spotted, with a narrow velum; macro- 

 spores 0.36 to 0.50 mm. thick, marked with minute, rather regular, distinct 

 or rarely confluent warts; microspores 0.024 to 0.029 mm. long, almost 

 smooth and brown. — Am. Naturalist, 8. 214. 



Found only once, deeply immersed in a cold alpine stream on the east- 

 ern slope of the Mono Pass, California, 7,000 ft. alt., H. Bolander.—This 

 curious diminutive species is a close ally to the last by the structure of the 

 leaves and the mode of living, but is widely separated from it by the sculp- 

 ture of the spores; the shortness of the epidermis cells is quite peculiar to 

 it, and so are the close transverse partitions,; the walls of the leaf and the 

 dissepiments are thinner than in the last, consisting of only a few layers 

 of cells. The minute tubercles of the macrospores are most distinct on 

 the lower surface, but become sometimes confluent on the upper side. 



3. I. TucKERMANi, A. Braun in litt. A small plant with very slender 

 tapering olive- green leaves (10 to 30 in number, mostly 2 to 3 inches long), 

 the outer recurved, walls and partitions rather thick for the diameter of the 

 leaf; sporangium mostly oblong, white or rarely brown-spotted, the upper 

 third covered by the velum ; macrospores 0.44 to 0.56 mm. diam., the up- 

 per segments marked with prominent, somewhat parallel and branching 

 ridges, the lower half reticulated ; microspores smooth or nearly so, 0.026 

 to 0.032 mm. long. — Engelm. in Gray Man. 1. c. 676. 



In several ponds and streams near Boston, maturing from August to 

 October; first discovered by E. Tuckermaiin, 1S48, in the Mystic river 

 very near where it issues from the pond ; in the same locality and in 

 Mystic, Spy and Horn ponds, W. Boott, "always immersed in fresh wa- 

 ter, sometimes only a few inches below the surface, often in places which 

 are subject to a tide of almost two feet in height, generally gregarious 

 and carpeting the bottom with an olive-green turf." The leaves are usually 

 not longer than two or three inches, and, at least the outer ones, recurved; 

 occasionally, in slender specimens, probably from deep water I have 

 seen them straighter and over 5 inches long. The sculpture of the spores 

 is very characteristic, wavy, somewhat branching ridges run from the 

 three upper commissures in right angles; on the lower surface they inter- 

 lace, covering it with an irregular network. Some specimens collected by 

 Mr. Boott at the end of October seem to indicate a second growth, as 

 within the circle of microspore-bearing leaves, and after the outer ones 

 with their macrosporangia had fallen, an inner growth bearing macrospo- 

 rangia was noticed. One of his specimens is of particular morphological 

 interest, as it shows four heads or leaf-buds from the same healthy and 

 vigorous trunk, three close together on top and a fourth on the side, sepa- 

 rated from the others by a deep incision in the trunk. This division of 

 the axis did not result from any proliferation of the leaves, but most 

 probably from a lesion of the centre of vegetation, and is of very rare 

 occurrence in this genus, where the simplicity of the axis is so particularly 

 marked (see above p. 358). 



