ZONE OF AMMONITES PLANORBIS. 59 



collection I find there was a specimen of Ichthi/osmirus intermedius, about 8 feet in length ; 

 the two fore-paddles and a portion of the scapular arch were tolerably complete ; and 

 there were upwards of 100 vertebrae and ribs nearly all in place. /. tenuirostris ; 4 feet 

 in length ; the skulls, jaws, and teeth well preserved, the vertebral column tolerably 

 complete; and likewise one forc-paddle. I. commvnis ; very fine paddles. I. platyodon ; 

 large skull, with orbital plates in position. Plesiosaurus Hawkinsii ; the vertebral column, 

 ribs, and humeri ; and fifty vertebrae in position. 



The Ostrea and lower Saurian beds at Bin ton, Brockeridge, and Street are overlaid by 

 clays and laminated shales, containing Ammonites planorbis. As these beds form a most 

 important horizon in the Lias formation, and have a wide geographical distribution in 

 England, France, and Germany, they require to be defined with accuracy, especially as 

 some authors are of opinion that the true Lias commences with this zone of life. 



The relation of the Am. planorbis shales to the Saurian beds below is extremely well 

 exposed in the Railway-cutting at Uphill and in the quarries at Street, Binton, and 

 Wilmcote, in Warwickshire, at Brockeridge Common, in Gloucestershire, and at Strensham, 

 Worcestershire, and to the Am. Biicklandi or Lima beds above in the sections at Saltford, 

 near Bristol ; Penarth Head, near Cardiff"; and Pinhay Bay, near Lyme Regis. 



The following section of the beds at Binton was made by Mr. Robt. Tomes, of Welford 

 Hill, near Stratford-on-Avon, from a quarry now abandoned. A similar exposition, 

 however, is seen in the quarry worked near the former, the various beds of which I have 

 examined and measured with Messrs. Tomes and Kershaw, 



Section of the Zones o/" Ammonites planorbis «mc^ Avicula contorta, at Binton, 



Wanoicksldre. 



LiTHOLOGY. Thickness. Organic Remains ; and Local Names of the Beds. 



No. ft. in. 



1. Light-coloured limestone 6 "Toprock''or "Whites." 



2. Light-coloured clay 2 6 



3. Argillaceous limestone 3 "Top Liveries." Ichthyosaurus; on the upper 



surface ; Insects. 



4. Light-coloured clay 7 



5. Argillaceous limestone 3^ "Top Liveries" (lower). Insects; Ammonites 



Johnstoni, Sow. 



6. Clay 1 1 



7. Grayish limestone 6 "Extrarock." " Thick paving-bed." No fossils. 



8. Clay 3^ 



9. Grayish limestone. Thin and irregu- " Quarters." 



lar when covered by the preceding 



2 in. to 3 



10. Clay 8^ 



11. Grayish limestone. A constant bed . 3| "Ribs." Insects. 



12. Clay 5^ 



