300 GEOLOGICAL SURVEY OF THE TERRITORIES. 



around a tergescence of the lower part, formed by an abnormal growth, 

 of radicles. The upper surface of the leaves is somewhat rough ; the 

 lower surface, inside of the fringe, is dotted with minute holes, or like 

 spongious. The leaves are generally mixed, or superposed to thin foli- 

 form long radicles, all of the same size, coming in bundles from linear 

 rootlets, two to five millimeters thick. They form a thick coating sur- 

 rounding the leaves, or whereupon the leaves are floating, without evi- 

 dent connection or point of attachment to them. 



At first I supposed these leaves as representing the same species as 

 the following, but their relation to species of Pistia, whose leaves are flat 

 and not like vehicles, seems to indicate, though the likeness in some of 

 the characters may be, that these organs represent two kinds of water- 

 plants. Comparing this one to leaves of Pistia spathulata, Mich., from 

 specimens of Louisiana, the affinity is remarked not only in the obovate 

 shape of the leaves, but in the kind of nervation, by inflated primary 

 veins diverging from the base of the pedicel, where they pass into bun- 

 dles of radicular filaments of the same characters as those of the fossil 

 plant. Most of the leaves of the living species, the old ones especially, 

 bear from the middle to the base an inflated spongious coating similar 

 to that which is observed on the under surface of the fossil leaves. The 

 more marked difference is in the central part of the fossil species, which 

 appears surrounded by a distinctly-marked deep line, while in the leaves 

 of P. spathulata the thick zone, though definite, terminates in passing up- 

 ward along the primary veins ; but this difference, like that of the areo- 

 lation along the borders, is specific only and the generic identity appears 

 clearly defined. 



Habitat.— Point of Rocks, very abundant, and covering by itself only 

 large surface of shale, Dr. F. V. Hayden, Wm. Glebum. 



10. Lemna Scutata, Daws. 



Fronds round, entire, slightly undulate on the edges, sometimes an inch 

 in diameter, single or grouped ; roots numerous, filiform, proceeding 

 from a round spot near the notch of the frond. 



To this species, as described and figured by Professor Dawson (Report 

 on the Geology of the Forty-ninth Parallel, Appendix A, p. 329, Tab. XVI, 

 figs. 5 and 6), I refer a number of round bodies, leaves or fronds, mixed 

 with the species described above. Comparing them with the author's 

 figures, there is no difference whatever, except that if some of them do 

 not show any trace of veins, others, exactly of the same shape, are 

 veined from the base, where the radicular filaments are attached to them 

 and the veins distributed as in the former species. Some specimens also, 

 one of which has been figured, show the basilar part inflated, or the 

 pedicel wherefrom the veins are diverging, just in the center of the cir- 

 cular organism, as if it had been a bladdery or vesicular plant, flatteued 

 by compression. I still believe that both the leaves described above 

 and these represent the same kind of vegetable, these being the young 

 and yet undeveloped organs. All the different appearances of these 

 plants, represented by numerous specimens, have been figured, and the 

 comparison of their various forms will, I think, satisfy paleontologists 

 in regard to their relation to a species of Pistia. 



Habitat. — Point of Eocks, mixed with the former, Dr. F. V. Hayden, 

 Wm. Glebum. 



11. Ottelia Americana, sp. nov. 



Spathe ovate narrowed to a round pedicel, surrounded by an undu- 

 lated and wrinkled fringe, emarginate at the top. 



