48 



Group THALLOPHYTA. 

 Class ALG.E. 



The few specimens described as Algae from the Inferior Oolite 

 rocks of Yorkshire are either too imperfect to determine, or in 

 all probability may be more correctly regarded as impressions of 

 thalloid Liverworts. Lindley & Hutton 1 described a fossil from 

 Gristhorpe under the name Fucoides arcuatus, and the same species 

 is figured in the third edition of Phillips' Geology of the Yorkshire 

 Coast 2 ; there is little doubt, however, that the type-specimen 

 of Lindley & Hutton is an imperfect example of Leckenby's 

 Fucoides erectus, 3 a species now placed in the genus Marchantites. 

 A still more imperfect fossil from Gristhorpe, named by Phillips 

 Fucoides diffususf may also be doubtfully referred to Leckenby's 

 species. 



[RiPPLE-MAKKS SIMULATING A PLANT. 



40,565. PI. XIX. Fig. 6. 



The specimen represented in PI. XIX. Fig. 6 was labelled by 

 Bean " Lepidodendron ? from the Upper Shale of Scarborough," 

 and in the Museum Register the same piece of shale is described 

 as a fern stem. On one side of the rock there is a series of 

 irregularly parallel ridges; and on the other face, as shown in 

 Fig. 6, two sets of ridges intersect, dividing the surface into 

 a number of depressed areas, which present a slight resemblance 

 to a partially decorticated Lepidodendroid stem. The ridges are 

 no doubt ripple-marks produced on the surface of an argillaceous 

 sand; the specimen is of some interest as illustrating a possible 

 source of error, and agrees very closely with a photograph of 

 intersecting ripple-marks figured by Williamson 5 in 1885. 



Upper Shale : Scarborough. Bean Coll.] 



1 Lindley & Hutton (36), pi. 185. 



2 Phillips (75), p. 195, lign. 1. 



3 Leckenby (64), pi. xi. fig. 3. 

 * Phillips (75), p. 196, lign. 2. 



5 "Williamson (85), pi. iii. fig. 14. 



