parti] THE SHALES-WITH-' BEEF.' 47 



3. Shales-imY/*-' Beef,' a Sequence in the Lower Lias of the 

 Dorset Coast. By William Dickson Lang, Sc.D., F.G.S., 

 Leonard Frank Spath, D.Sc, F.Gr.S., and William Alfred 

 Richardson, M.Sc, F.Gr.S. (Read January 4th, 1922.) 



[Plates III & IV.] 



Contents. 



Part I. Stratigraphy. (By W. D. L.) 



Page 



(A) Introduction 47 



(B) Nomenclature of Rock-Forms 52 



(C) General Description 54 



(D) Detailed Description 57 



Part II. Palaeontology : The Ammonites. (By L. P. S.) 



(A) Introduction 66 



(B) Genus Arnioceras 68 



(C) Do. Agassiceras 72 



{D) Do. Paramioceras 73 



(E) Do. Arietites : ." 74 



(P) Do. Cymbites 76 



(G) Do. Sulciferites 78 



(H) Do. Microderoceras 81 



{I) Do. Xipheroceras ...' 82 



(J) Summary of New Names 83 



(K) General Results 84 



Part III. Petrology. (By W. A. R.) 



(A) Laminated Shales 88 



(B) The Occurrence of Barytes 88 



(C) The Veins of ' Beef ' 89 



(D) The Cone-in-Cone Structure in the ' Beef ' 91 



(E) The Calcareous Nodules 95 



(F) Sedimentary History of the Beds 97 



Part I. Stratigraphy. 



(A) Introduction. 



SiiALES-wiTn-' Beef ' l was the name given to some 70 feet of 

 Lias on the Dorset coast, tying above (53) Table Ledge and below 

 (76 a) the Birchi-Tabular. The beds consist of paper-shales, 

 marls, indurated bands, and limestone nodule-beds, with numerous, 



1 W. D. Lang, Proc. Geol. Assoc, vol. xxv (1914) p. 313. 



