Prof. P. F. Kendall — Equisetites on Yorkshire Coast. 7 



attempt of the plant to liold its own against the overwhelming sand. 

 Similar cases of preservation are known from the Carboniferous 

 formation, and have generally been regarded as proofs of an occurrence 

 in situ and as resulting from the even balance between the growth of 

 the plant and the silting up of its habitat. Some figures of Coal- 

 measure plants given by Grand' Eury illustrate practically the same 

 conditions, especially one showing a very fine group of Calamifes 

 SugTcowU from the Carboniferous of Central France ; and Grand'Eury's 

 interpretation of the structure of this specimen is similar to the one 

 applied here to the Yorkshire Equisetites. 



If this interpretation of the vertic'al Equisetites stems is right, it 

 will be seen to throw some light on the conditions under which the 

 surrounding sandstone was laid down. On the spots where the 

 Equisetites stems grew during the accumulation of the sand, the water 

 must have been comparatively shallow, as the tops of the stems, at 

 least, reached above the surface. The vertical casts cannot, as a rule, 

 be followed for more than a few feet, yet it appears highly probable 

 that the same conditions of sedimentation prevailed during the 

 accumulation of thick banks of sandstone. The two specimens 

 figured here come from beds at different levels in one and the 

 same section of the sandstone, and it may be concluded with some 

 probability that the intermediate beds were formed in the same 

 manner too. There is no reason to regard the cases here described 

 as mere exceptions. I am inclined to believe, both from the 

 descriptions of the older writers and from my own observations, 

 that the upright stems of Equisetites which are so common in the 

 sandstones as a rule have been preserved under similar conditions, 

 in which case the sandstone too should have been deposited in a 

 uniform manner. It would be natural to imagine that the Equisetites 

 grew in large, shallow fresh- or brack-water lagoons or protected 

 estuaries with low marshy shores, and that these lagoons or estuaries 

 were gradually becoming filled up by accumulating sand, the area 

 being, during this process, slowly subsiding. The whole question, 

 however, requires much more extensive observations, and it certainly 

 deserves to be made the subject of special studies. 



III. — Notes on the Stratigkaphical Position of Beds with 



Equisetum. 



By Professor Percy Fey Kendall, M.Sc, F.G.S. 



DR. NATHORST mentioned to me in 1910 the fact that the 

 rhizomes of Equisetum columnaris had not been observed, and 

 I offered to show him a place where I thought they would be found. 

 He had not time to visit the section on that occasion, but in the 

 following year Dr. T. G. Halle accompanied me to the exposure and 

 agreeably to expectation the rhizomes were found within a few 

 minutes of our arrival. 



The section is exposed at the Peak Alum Works (now Brick-works), 

 where a splendid sequence is exhibited, extending from the Alum 



' C. Grancf'Eury, Flore Carbonifere du Diimrtement de la Loire et du centre 

 de la France, Paris, 1877, p. 15, pi. i, fig. 1. 



