Geologists' Association. 383 



following species : — Canis lupus, Hycena crocuta (spelcea), Felis leo 

 (spelcsa), Castor trogontherium and fiber, Elephas primigenius and 

 antiquus, Hippopotamus amphibius, Rhinoceros tichorhinus (a Rhino- 

 ceros of doubtful species), Sus scrofa, Equus asinus and caballus, 

 Bos primigenius, taurus f, and indicus ?, Bison priscus and Europceus, 

 and Cervus taranclus, Belgrandi, megaceros, Canadensis ?, elapJms, and 

 a small species. 



Geologists' Association. — June 7, 1872. — The Rev. T. Wilt- 

 shire, President, in the Chair. — 1. " On the Classification of the 

 Cambrian and Silui-ian Rocks," by Henry Hicks, Esq., F.G.S. 



The author, after mentioning the groups now known to comprise 

 the Cambrian and Silurian Rocks, as exhibited in the British Isles, 

 and the usual mode, hitherto, of dividing and sub-dividing these 

 formations, stated that it was impossible, in a science so progressive 

 as Geology, where new discoveries were continually being made, to 

 accept at present any of these arrangements, which for the most 

 part had been made some twenty or thirty years ago, unless with 

 considerable modifications. The classification approved by the 

 author has already been, to a great extent, adopted by Sir Charles 

 Lyell, in his "Student's Manual," and by the late Mr. Salter and 

 the author in papers to the British Association, and is based on the 

 most recent palaeontological and stratigraphical evidence. In a 

 table exhibited for the purpose of illustrating these facts, the classi- 

 fication of Prof. Sedgwick and of Sir Roderick Murchison were 

 placed side by side along with the one proposed. 



The columns in the table showed (1) the lithological characters 

 of the beds comprising each group, (2) the thickness of the strata, 

 (3) the organic remains contained in each group, (4) the number of 

 genera and species which are known to reach from one group into 

 another, (5) the order of the appearance of animal life upon the 

 globe, and (6) the localities where the several groups are best seen 

 in England. 



By means of the evidence set forth in these columns, the author 

 was enabled to show the most natural divisions and sub-divisions, so 

 far as recent researches are capable of explaining them. 



The following are the chief divisions, accepted as being the most 

 satisfactory at present : — The Lower Cambrian, to include the Long- 

 mynd (Harlech grits and Llanberis slates, and the rocks at Bray 

 Head, etc.), and the Menevian groups, which were shown to be 

 intimately connected palceontologically, and to be entirely distinct in 

 their faunas from the overlying rocks. 



The Upper Cambrian, to include the Lingula Flags (Lower, Middle, 

 and Upper — called also Maeutwrog, Ffestiniog, and Dolgelly or 

 Malvern) and the Tremadoc groups. These were also shown to be 

 connected closely by some of the genera, especially by Olenus, Cono- 

 coryphe, and Dilceloceplialus. 



The Xoiyer Silurian, to comprise the Arenig (Lower and UiDper, the 

 former a series only recently known through the researches of the 

 author, and forming a connecting link between the Tremadocs and 

 the true Arenig rocks), the Llandeilo (Upper and Lower, the former 



