364 



fronds, and forming in ascending, and by a kind of abnormal anastomosis, 

 irregularly polygonal large meshes. The area of the inflated and central 

 ■part is separated by a deep narrow groove from the flat margin which 

 surrounds it, and whose areolation is disconnected and distinct, repre- 

 senting large quadrangular areolte, whose subdivisions curve along the 

 borders in festoons. Sometimes, however, the central part does not appear 

 inflated; and sometimes, also, in specimens which seem to represent 

 young plants, no trace of borders is perceivable. The radicles all 

 equal in size, filiform, come out in bundles from divisions of short roots, 

 or rhizomas, and form a thick coating wherein the plants were super- 

 posed or floating; for they appear often surrounded by these filaments 

 or immersed into a matting of them. The point of connection of these 

 rootlets to the fronds is rarely distinct. The only specimen where I 

 could see it clearly is represented in one of the figures; and even this 

 case is not conclusive evidence for all the fronds ; for in some ones, 

 the base of the fronds or of the pedicels seems attached to a kind 

 of floating thallus. The upper surface of these plants is slightly rough ; 

 the central part, inside of the fringe, is somewhat thicker ; and the lower 

 surface is dotted with minute holes or apparently spougious. 



One of the specimens seems to represent a fruit, or a different species of 

 the same genus. The central nucleus is oval, three and a half centimeters 

 long, two centimeters broad, somewhat tumescent, marked lengthwise by 

 irregular stride, or wrinkles, surrounded by a sinuate border six to eight 

 millimeters broad, laterally wrinkled, narrowing downward to the point 

 "where it joins the short pedicel, which is one and a half centimeters long 

 and two millimeters broad at its base. The central part of this fruit, or 

 frond, is thicker and apparently more compact than in the other form, 

 and the specimen which represents this variety, or species, is unique. 

 No trace of nervation or areolation is discernible upon its surface. 



I do not know as yet to what family of plants these peculiar organ- 

 isms are referable. In the Geological Keport of Prof G. M. Dawson in 

 the Vicinity of the Forty-ninth Parallel, Prof. J. W. Dawson has de- 

 scribed and figured (in appendix, p. 329, PI. XVI, figs. 5-6), under the 

 name of Lemna scutata, a plant which appears to be the same as ours, 

 or which is, at least, very closely allied to it. The characters, however, do 

 not agree with those of Lemna. The rootlets marked at the base of the cir- 

 cular fronds seem to prove that these organs were like vesicles, or were in- 

 flated, like those of our plate; for, if they had been flattened upon the 

 surface of the water like Lemna fronds, the rootlets would not appear on 

 one side of the frond or at its base. This species is represented by more 

 than fifty specimens. 



Habitat.— Point of Eocks, Br. F. V. Eayden. 



2. Fucus LiGNiTUM, sp. nov. 



Frond flattened, irregularly dichotomous ; branches diverging ob- 

 liquely ; branchlets short, terminal, linear-divaricate, tufted, forking at 

 the point. 



The fragment figured is the only one of this kind in the specimens. It 

 represents a species allied to Sphccrococcns crispi/ormis, Sternb., as de- 

 scribed in Heer's Flor. Tert. Helv. (p. 23, PI. IV, fig. 1), and still more, 

 perhaps, to the living Fucus canaUculatus, Agh., very common along the 

 coasts of the Baltic Sea, and also discovered in numerous specimens in 

 the Tertiary of Spitzbergen. The base of the lowest branches is four milli- 

 meters broad, but the size of the branchlets diminishes nearly one-half at 

 each dichotomous division. The terminal branchlets are only half a 

 millimeter broad, fasciculate-dichotomous, short, split, or furcate at the 



