40 



THE LTAS AMMONITES. 



by Barry Island, Aberthaw, and Dunraven Castle, to the month of the River Ogmore, 

 where the Lower Lias rests on highly inclined beds of Carboniferous Limestone. The 

 strata laid bare by the sea are chiefly those containing Lima gigantea and Gryphcea 

 arcuata. At Cowbridge the same stratigraphical condition is observed, and the Lower 

 Lias is here seen resting on Carboniferous Limestone. At Penarth Head, however, the 

 relation of the Bucklandi to the Planorbis and Avicula contorta beds is much better seen 

 than at any other part of the Glamorganshire coast. 



The Rev. J. E. Cross, F.G.S., has described the Lias beds of North-west Lincoln- 

 shire, 1 which have recently been laid open by the extension of railways and searchings 

 for Ironstone, and from his interesting and instructive paper I have deduced the 

 following results. 



A generalised profile of the Lias beds of North-west Lincolnshire. 

 Lincolnshire Oolitic Limestone. 



Horizons. 



Petrology. 



Paleontology. 



Upper Lias. 



Blue shale with moulds 

 of Ammonites of the 

 falcifer type, 60 feet 

 thick. 



Harpoceras serpentinum, Lytoceras cornucopia. 



Middle Lias 

 Marlstone. 



Hard, light grey lime- 

 stone, weathering to 

 brown Ironstone with 

 Rhynchonellse, 8 feet 

 thick. 



Amaltheus spinatus, Avicula cygnipes, Terebratula punc- 

 tata, Rhynchonella tetraedra, Spiriferina rostrata. 



Middle Lias. 

 Marls. 



Blue clay with cement 

 nodules throughout, 

 containing Aegoceras 

 capricornus, 66 feet 

 thick. 



Aegoceras Henley <i =: capricornum, Belemnites fraxillosus, 

 Plicatula spinosa, Avicula incequwalis, Nucula com- 

 planata, Lima acuticosta, Rhynchonella variabilis. 



Middle Lias. 

 Ironstone. 



The Ironstone Pecten- 

 bed, crowded with 

 shells, 4 feet thick. 



Aeg. armatum, Aeg. striatum, Belemnites elongatus, Car- 

 dium multicostatum, C. hybrida, Myacites unionides, 

 Tancredialiassica, Pecten Icevis, in great numbers and 

 of good size. 



Oxynotus and 

 raricostatus zones. 



Blue Marls of the 

 Lower Lias, containing 

 different zones of life, 

 90 feet thick. 



Aegoceras Birchii, Amaltheus oxynotus, Arietites rari- 

 costatus, Aeg. Taylori, Aeg. Loscombi, Aeg. natrix, 

 Belemnites paxillosus, B. clavatus, Gryphcea Maccul- 

 lochi, Terebratula numismalis, Pinna folium, Phola- 

 domya ambigua. 



1 • Quart. Jour. Geol. Soc./ vol. xxxvi, p. 115, 18/5. 



