ZONE OF LYTOCERAS JURENSE. 



141 



Fig. 9. — Section across Bundry Hill, shoxoing its cap of Inferior Oolite. 



a q i 



a. Inferior Oolite. 



b. Upper Lias. 



c. Middle and Lower Lias. 



d. New Red Sandstone. 



g. Quarries of Oolitic Limestones. 



s. Origin of the springs of water. 



EiG. 10. — Lateral prof le of Dundry Hill. 



7. Freestone Building Oolite, 12 feet. 

 6. Fine-grained Oolite 4 „ 



5. Shellv Ragstones 8 „ 



4 & 3. Rubb'ly Shelly Limestones, 12 „ 

 2. Zone of Harp. Sowerbii 3 „ 



1. Ironshot Pleurotomaria Bed, 2 feet. 



a. Upper Lias Sands 2-3 ,, 



b. Upper Lias Clay 4 „ 



c. Middle Lias 1 „ 



d. Lower Lias 369 „ 



The Oolitic rocks exposed at the summit of the hill belong to the Inferior Oolite, 

 which, ill the south of England, admits of a division into three zones of life. The lower 

 resting upon the Upper-Lias Sands has Harpoceras MurcJdsoncB as its leading fossil ; 

 the middle contains a large assemblage of Mollusca, among which the Ammonoida 

 predominate, and these chiefly belong to Stephanoceras Hmnphriesianum, Steph. 

 Bronyniarti, and Steph. Brocchii ; the upper zone is characterised by Cosmoceras 

 Parkinsoni, PerispJdnctes Martinsii, and Oppelia subradiata, with many Echinidse and a 

 large series of reef-building Corals. These three subdivisions are rarely all found 

 together in the same locality, but the order of their sequence in nature is, as stated, in 

 Dundry. 



1. In the ironshot shelly beds are many Lamellibranch Molluscs and a rich assem- 

 blage of Pleurotomarias. These are covered by the second Ammonite-zone with 

 Stephanoceras Humphriesianum. Many of these are beautifully preserved Ammonoida 

 with the shell entire, the mouth-processes developed, and the Aptychi in situ, as Stejihan. 

 Humphriesianum, Steph. Brocchii, Steph. Bronyniarti, Steph. Blaydeni, Steph. Gervillei, 

 and others. The Conchifera beds 3 and 4 contain Harpoceras Sowerbii and a large 

 assemblage of Lamellibranchs with Echinidse and Anthozoa belonging to the middle 



