Sohimper and Mougeot, in the Bunter of Nottingham. 403 



A further source of possible error depends on the fact that 

 this diagnosis is necessarily founded on fragmentary material 

 from various localities occurring in association with remains of 

 other plants. This latter objection does not apply to the fossils 

 described below since they appear to belong wholly to one species 

 and are not associated with any other plant-remains. 



Description of the Specimens. 



Detached leaves. These are fragments of long, narrow, deli- 

 cate, grass-like leaves, usually found detached but more rarely 

 occurring in organic connection with a stem. They have smooth 

 entire margins with a median group of exceedingly fine parallel 

 nerves. 



One example has four and another has six leaves, in each case 

 the margins of the leaves are arranged parallel to one another. 

 These specimens may be regarded as portions of sheath-segments 

 composed of several leaves, originally united by their smooth 

 margins along the commissural lines. By splitting along these 

 lines the leaves have, in some cases, become either partially or 

 wholly free. 



Leafy shoot. A cast of the external surface of a small stem 

 about "5 cm. in diameter with a smooth, irregularly wrinkled 

 surface, bears a node from which arise four or more leaves forming 

 a leaf-sheath. Only the basal portions of the leaves are preserved, 

 and the clasping nature of the leaf-sheath cannot be made out 

 because the specimen has been flattened by crushing. 



Leafless stems. The material furnishes at least four kinds of 

 casts and impressions of leafless stems : 



(a) The first type are characterised by a smooth, irregularly 

 wrinkled surface and distinctly swollen nodes. 



In these features they agree exactly with casts of the external 

 surface of leaf-bearing stems. 



(h) Occasionally a cast of the above type is folded into some- 

 what broad furrows and narrow ridges. 



A similar structure occurring in casts of Schizoneura meriani 

 was explained by Schimper * as due to an accident of preservation. 



(c) Several casts of portions of large stems differ from type 

 (<x) only in the fact that their smooth surfaces are faintly but 

 regularly ridged and grooved. They may be regarded as either 

 the casts of the external surface of large, faintly-ribbed stems, 

 or the ribbing may be ascribed to the action of the internal 

 structure. 



{d) What appears to be a more internal cast than the above 

 has internodes strongly marked with longitudinal ridges and 



* Schimper, Traite de Palaeontologie Vegetale, 1869, p. 282. 



