INCEKT2E SEDIS. 19 



and Ettingshausen, under the name Halyxerites gracilis, 1 from the 

 Cretaceous of Aachen and Maestricht. This so-called alga might 

 also be compared to a fragment of a filmy fern frond. 



V. 2330. PL I. Fig. 3. 



This specimen shows very clearly the habit of the plant, and 

 especially the marked contrast between the sharply defined black 

 midrib and the light brown impressions of the more delicate lateral 

 portions. Ecclesbourne. Rufford Coll. 



V. 23300. Practically identical with V. 2330. Ecclesbourne. 



Rufford Coll. 



V. 2334. Several smaller pieces of the branched thalloid body : 

 on the same slab of ironstone are fragments of Sphenopteris 

 Fontainei, sp. nov. Ecclesbourne. Rufford Coll. 



PLANTJ3 INCERT.E SEDIS. 



In PL I. Eigs. 7 and 8, two specimens are represented which 

 it is difficult to refer, with any degree of certainty, to definite 

 genera, but which may be briefly described here as possibly 

 referable to the Pteridophyta. 



Specimen A. PL I. Pig. 7. V. 2370. 



Ecclesbourne. Rufford Coll. 



The figure shows a clearly preserved and sharply cut black 

 structure projecting in a button-like form from the rock matrix. 

 In the centre is a distinct depression, and from this extend 

 numerous radiating ridges which curve downward at the periphery ; 

 these ridges appear to be the projecting midribs of leaf -segments, 

 which terminate acutely, and are fused together laterally in the 

 form of a circular sheath. I am inclined to regard the specimen 

 as an Equisetaceous leaf-sheath, but prefer to leave it unnamed 

 in the hope of fresh discoveries affording more definite evidence 

 as to its botanical position. 



1 Denkschr. k. Ak. Wiss. math.-nat. Cl. vol. xvi. 1859, p. 61, pi. i. figs. 1-2. 



