276 PTERIDOPHYTA. [CH. 



the Yorkshire Coast for some very imperfect stems from the 

 Lower Oolite rocks near Whitby'. The choice of the term 

 lateralis illustrates a misconception ; it was given to the plant 

 in the belief that certain characteristic wheel-like marks on 

 the stems were the scars of branches. Lindley and Hutton'' 

 figured a specimen of this species in their Fossil Flora, and 

 quoted a remark by "Mr Williamson junior" (afterwards Prof 

 Williamson) that the so-called scars often occur as isolated 

 discs in the neighbourhood of the stems. Bunbury^ described 

 an example of the same species with narrow spreading leaves 

 like those of a Palaeozoic Asterophyllites, and proposed this 

 generic name as more appropriate than Equisetites. In all pro- 

 bability the example shown in fig. 63 is that which Bunbury 

 described. It is certainly the same as one figured by Zigno' as 

 Oalamites lateralis in his Flora fossilis formationis Oolithicae. 



This specimen illustrates a further mis6onception in the 

 diagnosis of the species. The long linear appendages spreading 

 from the nodes are, I believe, slender branches and not leaves ; 

 they have not the form of delicate filmy markings on the rock 

 face, but are comparatively thick and almost woody in appear- 

 ance. The true leaves are distinctly indicated at the nodes, 

 and exhibit the ordinary features of toothed sheaths. 



Heer" proposed to transfer Phillips' species to the genus 

 Phyllotheca, and Schimper" preferred the generic term Schizo- 

 neura. The suggestion for the use of these two names would 

 probably not have been made had the presence of the Equisetum 

 sheaths been recognised. 



The circular depressions a short distance above each node 

 are the ' branch scars ' of various writers. Schimper suggested 

 that these radially marked circles might be displaced nodal 

 diaphragms. Andrae' figured the same objects in 18.53 

 but regarded them as branch scars, although in the speci- 

 men he describes, there are several of them lying apart from 



1 PhilUps J. (29) PI. A. fig. 13. ■• Lindley and Button (31) PI. clxxxvi. 



3 Bunbury (51) p. 189. ^ Zigno (56) PI. in. fig. 3, p. 46. 



» Heer (77) p. 4.S, PI. re. 



« Schimper (69) p. 284. Vide also Nathorst (80) p. 54. 



' Andrae (53) PI. vi. figs. 1—5. 



