518 Notices of Memoirs — A. G. Seward — Jurassic Plants. 



by the stream falling into the pot, are crystals of calcite. These are 

 very much water-worn, but clearly indicate the existence of a fault. 

 Gaping Gill consists of a vertical shaft, 365 feet deep, into which 

 the waters of Fell Beck fall. At a depth of about 190 feet is a ledge 

 some 12 feet wide : at this point a fault is very clearly to be seen ; 

 the fault has a downthrow of six feet to the south. The shape of 

 practically all the pot-holes is a further indication that they have 

 been formed as the result of faults : they are all much longer than 

 they are wide, and thin out at each end into a narrow crack. It is 

 also a noticeable fact that they occur in groups and in such positions 

 that it would have been impossible for a stream to form more than 

 one out of several. 



II. — Jurassic Plants frobi the Books of East Yorkshire. By 

 A. C. Seward, M.A., F.K.S. 



Historicnl. — The work of Young and Bird, entitled " A Geological 

 Survey of the Yorkshire Coast," was published at Whitby in 1822. 

 William Bean, John Williamson, and William Crawford Williamson 

 rendered excellent service in the early days of the geological 

 exploration of the Yorkshire coast. Several specimens collected by 

 local naturalists were sent to Adolphe Brongniart, and described by 

 him in his " Histoire des Vegetaux Fossiles," published in 1828. 

 The publication in 1829 of " Illustrations of the Geology of 

 Yorkshire," by J. Phillips, placed the geology of East Yorkshire 

 on a sound scientific basis. Numerous species of Jurassic plants 

 from the Yorkshire coast were figured and described in the " Fossil 

 Flora of Great Britain," by Lindley and Hutton, which appeared in 

 parts between 1831 and 1837. Important additions have been made 

 to the knowledge of Yorkshire Jurassic plants by W. C. Williamson, 

 Bunbury, Leckenby, Carruthers, Nathorst, and other writers. 



Geological. — The East Yorkshire rocks of Lower Oolitic age may 

 be said to consist of three important estuarine series, separated from 

 one another by thin bands containing marine fossils. The majority 

 of the plants have been obtained from the Lower Estuarine Series, 

 which includes the famous plant-bed of Gristhorpe Bay. 



BotauicnJ. — I, Equisetales : Equisetites colnmnaris is one of the 

 commonest and most characteristic plants of the Yorkshire flora. 

 II, FiLiCES : the Ferns are represented by numerous species, 

 including examples referred to the Cyatheace^, Osmundaceaj, 

 Schizaeacese, Dipteridinte, and Matonineje. Ill, Ginkgoales : the 

 genera Ginkgo and Baiera ai'e both represented by several forms. 

 IV, Cycadales : Williamsonia, Nilssonia, and Otozamites are the 

 most conspicuous examples of this dominant class. V, Conifers : 

 the conifers are less abundant than either the Cycads or Ferns, but 

 the Araucarieae appear to have occupied a prominent position in the 

 vegetation. 



The author next gives an account of the composition of the 

 Yorkshire Jurassic vegetation as compared with that of the floras 

 of the same geological age in other parts of the world, and makes 

 suggestions for future work. 



