W. D. Lang — Lower Plienshachian of Charinouth. 401 



1910. Thomas, I. The British Carboniferous OrthotetincB (Mem. Geol. 



Surv. Gt. Brit., Palseontology), vol. i, pt. ii, pp. 99-100. 

 1912. Willis, Bailey. "Index to the Stratigraphy of North America " : 



U.S. Geol. Surv., Prof. Paper 71, pp. 401-24. 



EXPLANATION OF PLATE XII. 



Figs. 1-7. Syringothyris aff. carteri (Hall). Carboniferous Limestone 



Series, Sub-zone K2: Howie Hill, Forest of Dean area. 



Transverse sections of pedicle valve. Natural size. 

 ,, la-7a. Delthyrial supporting-plates and tube-bearing plate of the 



previous sections, enlarged. X 3. 

 ,, 8-8a. Syringothy7-is aff. carteri, Hall. Z]. . Mitcheldean. Fig. 8, 



internal cast of the pedicle valve, diagrammatic, showing 



the rod (r) representing the cavity of the syrinx ; Fig. 8a, 



transverse section, diagrammatic. 

 ,, 9-11. S23irifer dziplicicosta, ThiiiiT^s. Carboniferous Limestone : Park 



Hill, Derbyshire. Transverse sections of the pedicle valve. 



X 3. In Fig. 11 only the central portion of the section is 



indicated. 



ly. — The Lower Pliensbachian — ' CAHixiAisr ' — op Charmouth. 

 By W. D. Lang, M.A., F.G.S. 



I. The Green Ammonite Beds. 



THE Green Ammonite Beds of the Lias (called also the Wear Cliff 

 Beds in the latest Survey publication on Lyme Regis) ^ include 

 the clays with occasional limestones that lie between the Belemnite 

 Stone below and the lowest of the Three Tiers above. The lowest 

 Tier contains ammonites of the marffariiattcs grou-p,^ and the Belemnite 

 Stone caps the top beds of the Belemnite Marls that may^be placed 

 in the ihex-valdani zone.^ So the Green Ammonite Beds may be 

 said to constitute the upper part of such of the Pliensbachian or 

 Charmouthian as lies below the. Domerian.* Buckman has applied 

 the term ' Charmouthian ' to this lower portion, thus restricting the 

 term to a part only of what it originally included. * I have already 

 advocated the propriety of applying the term Charmouthian strictly 

 with its original connotation,^ and would call those zones of it that 

 lie below the Doraerian, — Bonarelli's ' Charmoutiano inferiore' — 

 which certainly need an inclusive name, Carixian.' The fullest 

 published accounts of the Green Ammonite Beds are those in the 



' Woodward & Ussher, The Geology of the Country near Sidmouth and Lyme 

 Begis (Mem. Geol. Surv. Eng. and Wales), 1911, 2nd ed., p. 31. 



■' Throughout this paper the phrase "ammonites of the — group " is used, 

 rather than the specific name of the ammonite, implying that several, presumably 

 related forms are included under one designation. 



^ On the evidence of Acanthopleuroceras ellipticum (James Sowerby), a form 

 that comes very near to A. valdani. Mr. S. S. Buckman kindly identified this 

 form for me. 



* Bonarelli, Atti della E. Accad. d. Scienze di Torino, vol. xxx, pp. 84-5, 1894. 



^ Buckman, Yorkshire Type Ammonites, pt. ii, p. xvi, 1910. 



^ Lang, Geol. Mag., Dec. V, Vol. IX, p. 284, 1912. 



'' "Charmouth, the Carixa of Eavennas " (Eoberts, The History of Lyme 

 Regis, Dorset, 1823, p. 220). The derivation seems obvious — Char-isca, 

 ' Char-river.' 



DECADE V. — VOL. X. — NO. IX. 26 



