ON NEMATOPHYTON AND ALLIES. 47 



Our examination indicates that the fossil consists of a mass of leaf-like organs, which, 

 under the influence of partial decay, or through contained mucilage, became closely mat- 

 ted together. Subsequently, a portion was broken away from the mass, and after drifting 

 an unknown distance, lodged and became fixed in the sand as found. This is the only 

 view which appears to satisfactorily account for the peculiar form and character of the 

 specimen. 



That the laminse are not the leaves of a vascular plant, is obvious from their struc- 

 ture, according to which we can only refer them to some Alga, of which they appear to 

 have constituted the thallus. That this latter must have been narrow, or else composed 

 of narrow divisions like the thallus of a Fucus, is suggested by the fact that all the 

 lamiuœ showing entire margins do not exceed 1.6 cm. in width, while most of them are 

 scarcely more than 0.5 cm. wide. 



That the openings in the laminae are cryj)tostomata seems to admit of little doubt, 

 and this fact goes far to establish the true character of the fossil as algoid. 



That these structures have an algoid character, and that they occur in the same beds 

 with Nematophytou, suggests their possible connection with that plant as its fronds. 

 This, however, must obviously remain a mere suggestion, since no further connection 

 between the two can be traced at present. 



Description of Figures. 



Plate I. 



JVematophyton Logani, Dn. 



Fig. 1. — Longitudinal section, showing the peculiar interlacing of the cells, x 27.5. 



Fig. 2.— Transverse section, showing a double " growth ring" ; also a radial opening passing through the centre of 

 the figure, with two smaller and isolated openings to the left x 27.5. 



Fig. 3.— Transverse section, showing a single " growth ring " crossing the figure transversely ; and a radial open- 

 ing. X 56. 



Fig. 4.— Longitudinal section of the same, showing the general character of the structure ; also, in radial section, 

 a short radial opening, as represented on the left of Plate I, fig. 2, into which the cells of the medulla are 

 seen to penetrate. x 56. 



Plate II. 



Nematophyton Logani, Dn. 



Fig. 5.— Longitudinal radial section taken from the left central portion of the radial opening in Plate II, fig. 2, 

 showing branching cells on the right and on the extreme left; also, two cells of the intercellular filaments 

 crossing a large cell in the upper right-hand corner of the field. The clouded appearance of the large cells 

 represents the disintegrated cellulose substance ; the clear areas are portions of the vermicular cells cut 

 away in making the section, x 154. 



Fig. G.— Transverse section of the same, showing the loose character of the structure and tlie thick-walled cells of 

 medulla turning into a radical opening, x 154. 



Nematophyton laxum, Pen. 



Fig. 7.— Longitudinal section showing the very loose and spongy character of the structure. The dark longitudinal 

 bands aie the large tubular cells of the medulla ; the finer, transverse lines are the intercellular filaments. 

 The specimen much less perfectly preserved than in the preceding, x 154. 



Fig. 8.— Transverse section of the same, showing the remote position of the cells of the medulla, the intercellular 

 structure forming a somewhat dense.mass. x 154. 



