622
THEORY AND PRACTICE OF ENGINEERING.
Rook II.
34th. — Scnlarida ; Vermetus, Scalari®, Dclphiimla.
35th. — Turbinidce ; Solarium, Rotella, Troehus, JVIonodonta, Turl>o, Planaxis,Phasianella, Turritella.
The Zoophaga form the next section.
36th Family.— Canalifera ; Ccrithium, Pleurotoma, Turbinella, Cancellaria,Fasciolaria, Fusus, Pyrula.
37th. — Alatte; Rostellaria, Pteroceras, Strombus.
38th. — Purpurifera ; Cassis, Cassidaria.
39th_ Columellidce; Columella, Mitra, Voluta, Marginella, Valvaria.
40th.— Convolutida; Ovula, Cypr ®a, Terebellum, Ancillaria, Oliva, Conus.
The fourth Order_ Cephalopoda.
41st Family. — Orthoceratidfc ; Belemnites, Orthoceras, Nodosaria, Ilip-purites, Conilites.
42nd. — Lituolitidce ; Spirula, Spirulina , Eituola.
43rd. — Craslicidce ; Renulina, Cristellaria, Orbiculina.
44tli. — Spherulidte; Meliola, Gyrogona, Melonia.
45th. — Radiolidida>; Rotalia, Lenticulina, Placentula.
46th.— Nautilidce; Discorbis, Siderolites, Polystomella, Vorticialis, Nummu-lites, Nautilus.
47th. — Ammonitida:; Ammonites, Orbulites, Ammonoceras, Turrulites, Bac-culites.
48th. — Argonauta.
49th. — Genus Octopus, Laligopsis, Loligo, Sepia.
Fifth Order, Ileteropoda.
50th Family_Genera Carinaria, Pterotrachea, Phylliroe.
Plants or Fossil plants; these are either terrestrial, fluviatile, or marine: when metwith in the blue clay they are often converted into jet, and sometimes their interior ischanged into carbonate of lime; in these cases their structure is very distinct. In a lime-stone which contains silica, or in calcareous sandstone, they are often found silicified; in thecoal-shales they are converted into coal ; in millstone grits there are only impressions ofthe plants, and the space they occupied contains a brown or yellow powder.
The races of plants found in the different strata all differ; the most numerous belong tothe following classes: Agamia; Cryptogamia cellulosa and vasculosa; Phanerogamiagymnospermia, monoeotyledonia, and dicotyledonia.
In the Newer Tertiary or Pliocene are found Zoophyta, Infusoria, Foraminifera , Molluscaacephala, Mollusca gasteropoda, Reptilia, Mammalia , &c.
In the Middle Tertiary or Miocene , Zoophyta, Mollusca acephala, Mollusca gasteropoda,and Mollusca pteropoda.
In the Older Tertiary or Eocene are Plant®, Zoophyta, the Mollusca , and Pisces.
In the Cretaceous system are Zoophyta, Radiata, Mollusca acephala, Mollusca brachiopoda,Mollusca cephalopoda, Pisces, and Reptilia .
In the Wealden formation are Plant®, Crustacea, and Reptilia .
In the Oolitic system are found Plant®, Zoophyta, Radiata, Insecta, Crustacea , Molluscaacephala, Mollusca gasteropoda, Mollusca cephalopoda, Pisces, and Reptilia .
In the Lias are Radiata, Mollusca acephala, Mollusca brachiopoda, Mollusca gaste-ropoda, Mollusca cephalopoda, Pisces, and Reptilia .
In the New' Red Sandstone are Radiata, Mollusca acephala, Mollusca brachiopoda,Mollusca gasteropoda, Mollusca cephalopoda, and Reptilia .
In the Carboniferous system and Magnesian Limestone are Plant®, Zoophyta, lladiata,Mollusca brachiopoda, gasteropoda, pteropoda, cephalopoda, and Pisces.
In the Devonian system and Old Red Sandstone are Zoophyta, Crustacea, Molluscabrachiopoda , gasteropoda, cephalopoda, and Pisces.
In the Silurian and Sub-silurian are Zoophyta, Crustacea , and the Mollusca brachio-poda, pteropoda, and cephalopoda.
In the British Isles we find the Pleistocene or superficial deposits, or what by some aretermed Diluvium and Alluvium, to consist of gravel and other transported materials, whichusually cover the regularly stratified rocks ; these in fact form the upper surface of ourisland, and therefore the first operated upon by the civil engineer.
The Newer Tertiary or Pliocene are the Norwich or Mammaliferous Crag, and the Till ofthe valley of the Clyde.
The Middle Tertiary or Miocene are the Coralline and Red Crag, the Older Tertiary orEocene, the Bagshot sand, and London clay.
The Newer Secondary Period, embraces first the Cretaceous System, which comprises theUpper Chalk with Hints, the Lower Chalk without any, Marl, Upper Green Sand. Gault,and Lower Green Sand.
The Middle Secondary comprises first the Wealden formation, which contains the Wealdclay, Hastings sand, and beds of Purbeck marble.