76 



MIDDLE LIAS. 



brick-earth; the finest specimens I have collected of Cardinia Listen, Sow., 

 Hippopodium ponderosum, Sow., Ammonites raricostatus, Ziet., and Pleurotomaria 4nffiica, 

 Sow., were obtained therefrom. In the railway-cutting at Bredon the same beds were 

 likewise laid open, and yielded a rich series of the characteristic fossils. In Warwick- 

 shire the railway-cutting at Honeybourne exposed the same beds ; and here also the Coral- 

 band contained a considerable number of Thecocyathus rucjosus, Wr. 



At Lyme Regis, in Dorsetshire, this zone is found near Black Venn. Some of the beds 

 contain a considerable quantitity of pyrites, so much so that during the winter months 

 they are worked for that mineral, when their characteristic Ammonites are collected in 

 considerable numbers ; unfortunately these fossils are so much charged with pyrites that 

 they are with difficulty preserved. 



At Robin Hood's Bay, on the coast of Yorkshire, this zone is seen resting on the 

 underlying clays with Ammonites oxrjnotus, and overlain by thick clays containing 

 Ammonites Jamesoni, Sow. In all these localities there appears to be an absence of 

 limestone-layers ; clay, more or less impregnated with iron, constituting the entire beds. 



Fossils of the Zone of Ammonites raricostatus. 



Belemnites acutns, Mill. 

 Nautilus striatus, Sow. 

 Ammonites raricostatus, Ziet. 



— armatus, Sow, 



— armatus densinodus, Querist. 



— iiodulosus. Buck. 



— Guibalianus, d^Orb. 



— muticus, d'Orb. (?) 

 Pleurotomaria similis, Sow. 

 Troclius imbricatus. Sow. 

 Chemnitzia parva, Wr., n. sp. 



Ostrea, raricostata, Wr, 

 Gryplisea obliquata, Sow. 

 Cardinia Listeri, Sow. 

 Hippopodium ponderosum, Sow. 

 Anomya pellucida, Terq. 

 Unicardiura cardioides, Phil. 

 Pleuromya oblonga, Wr., n. sp. 

 Rhynchonella variabilis, Schloth. 

 Terebratula numismalis, Lamlc. 

 Pentacrinus scalaris, Gold/. 

 Thecocyathus rugosus, Wr. 



THE MIDDLE LIAS. 



The Middle Lias is well developed in England, and fully exposed in the grand 

 natural sections of the Yorkshire and Dorsetshire coasts. In the Midland Counties it is 

 only partially shown. I therefore select a section of the cliffs east of Charmouth, Dorset, 

 which I made for this work last summer, with the assistance of my friend Mr. Day, as the 

 one that affords the best general view of the whole ; the Middle Lias here attains a 

 thickness of about 450 feet, and is divisible into five stages, each characterised by special 

 specific forms ; these in ascending order are — 1st. The zone of Ammonites Jamesoni. 

 2nd. The zone of Ammonites Ibex, 3rd. The zone of Ammonites capricornus. 4th. The 

 zone of Ammonites margaritatas. 5th. The zone of Ammonites spinatus. 



