744 MR ROBERT KIDSTON ON THE FOSSIL PLANTS OF 



The Geological Department of the British Museum subsequently obtained a collection 

 of fossil plants from Glencartholm, Eskdale, and among the specimens are the two 

 examples of Bythotrephis Scotica shown on Plate I. figs 1 and 2. 



The larger specimen, fig. 1, most probably represents a portion of a frond from 

 near the base. All the segments are broken, and the lower part of the fossil is also 

 incomplete. This specimen, which is fully six inches long, -illustrates well the 

 dichotomous division of the frond. The lower part of the fossil is half an inch broad, 

 but about three-quarters of an inch from its base it swells out considerably, and is here 

 nine-tenths of an inch wide, but this width most probably represents the measure- 

 ment of two contiguous segments; and though the fossil does not here show any line 

 of division, in all likelihood the separation of the segments extended further clown, but 

 from their close proximity the line of separation has been obliterated through pressure. 

 These branchlets again dichotomise, the segments becoming more narrow, till at their 

 upper extremity, where they are broken over, they are only one-fifth of an inch broad. 



In the other example, fig. 2, which is only 2 J inches long, the length of the 

 branchlets between the bifurcations is not so great as in the previous example, and it 

 is possibly a portion of a frond nearer the apex. 



Immediately above the base of the fragment it divides into two branches, each of 

 which again dichotomises. These attain rather more than an inch in length, when 

 they give rise to a third set of dichotomous segments. The branchlets which arise 

 from a dichotomy are slightly contracted at their base, and the summit of the segment 

 from which they spring is also constricted. In no case have I been successful in 

 observing the termination of a segment ; but from the manner in which they regularly 

 decrease in width, there is probably only a very small portion of the upper part of this 

 specimen wanting. 



As the segments are frequently bent over each other, the alga has evidently been 

 of a flaccid nature, but as the fossils are represented on the matrix not only by a well 

 defined carbonaceous stain, but have a quantity of carbonaceous matter adhering to 

 them here and there, the plant must have originally possessed considerable consistency. 



My thanks are due to Dr A. Smith Woodward, F.R.S., Keeper of the Department 

 of Geology and Palseontology, British Museum, for permission to figure these specimens. 



Locality. — Glencartholm. 



Spirophyton, Hall. 



1862. Spirophyton, Hall, Contributions to Palseontology, — 16th Rept. on the Cabinet of Nat. Hist., p. 79. 



Spirophyton cauda-galli, Vanuxem, sp. 



1842. (Fucoidea) cauda-galli, Vanuxem, Nat. Hist, of Neio York, "Geol. of New York, part iii., 



Survey of the Third Geological District," p. 128, figs. 3 (1-2). 

 1803. Spirophyton cauda-galli, Hall, Contributions to Palssoid., — \6th Annual Rept. on the Cabinet of 



Nat. Hist., pp. 79-80, figs. 1-2. 



