685 



Class l.(«). The crystalline slates of central Skiddaw forest, and 

 the upper Skiddaw slate series. The whole is inorganic and inter- 

 mediate between Class I. and Class II. 



Class II., or Palaeozoic series. 



This class includes all the groups of formations between Class L 

 and the old red sandstone ; and is subdivided as follows : — 



1. Lower Cambrian Si/stem. — All the Welsh series under the Bala 



limestone. The two great groups of green roofing slate and 

 porphyry on the north and south side of the mineral axis 

 of the Cumbrian mountains. A small joart of the slates of 

 Cornwall and South Devon. ? A part of the slate series of 

 the Isle of Man, &c., &c. 



2. Upper Cambrian System. — A large part of the Lammermuir 



chain on the south frontier of Scotland. A part of the third 

 Cumbrian group, commencing with the calcareous slates of 

 Coniston and Windermere. The system of the Berwyns and 

 South Wales. The slates of Charwood forest. } All the 

 North Devon and a part of the South Devon series. The 

 greater part of the Cornish series. 



3. The Silurian System. — ^The upper part of the third Cumbrian 



group, chiefly expended in Westmoreland and Yorkshire. The 



flagstone series of Denbighshire. The hills on both sides 



of Llangollen. The region east of the Berwyn chain. The 



regions described in the papers of Mr. Murchison, from which 



the types of the system are derived. The lowest part of the 



culmifei'ous series. ? 



Over all the preceding comes the Old Red Sandstone — divided into 



three great natural groups in the country bordering the Silurian 



types of Mr. Murchison ; in the northern counties developed in a 



less distinct manner, chiefly in the form of great unconformable 



masses of conglomerate, appearing at irregular intervals between the 



preceding groups and the carboniferous series. 



Little notice is taken in the memoir of the crystalline unstratified 

 rocks associated with the several series. Any questions of classifi- 

 cation, bearing on their geological epoch, can only be determined by 

 the effects, produced by them on the stratified series, which mark the 

 period of their first protrusion ; but for the present this subject is 

 not touched on by the author. 



June 6th. — WiUiam Stark, Esq., of Norwich, was elected a Fel- 

 low of this Society. 



A paper was first read, " On Spirolinites in Chalk and Chalk- 

 flints ; " by the Marquis of Northampton, F.G.S. 



The fossUs described in this memoir were chiefly found in the 

 flints of Sussex ; and though above two hundred specimens, more 

 or less perfect, have been discovered by the author in that county, 

 he has very rarely met with the genus elsewhere. They have been 

 also found in the same county by the Rev. G. Smith and Mr. Wal- 

 ter Mantell. They occur more frequently in the grey than the black 



