The New Encyclopaedia Britannica, Volume 7Encyclopaedia Britannica, 1974 - Encyclopedias and dictionaries |
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Page 340
... present , lack- ing fin rays ; persistent notochord , without bone or cartilage ; bony skeleton , when present , formed in skin ; true gill arches absent , gill basket present . Habitat of fossil groups uncertain ; earliest probably in ...
... present , lack- ing fin rays ; persistent notochord , without bone or cartilage ; bony skeleton , when present , formed in skin ; true gill arches absent , gill basket present . Habitat of fossil groups uncertain ; earliest probably in ...
Page 341
... present . One genus , Palaeospondylus , many specimens , probably of a single species . Length about 4 cm . CLASS SELACHII ( sharks , skates , rays , and relatives ) Vertebrates with jaws ; dermal and endochondral bone ab- sent ...
... present . One genus , Palaeospondylus , many specimens , probably of a single species . Length about 4 cm . CLASS SELACHII ( sharks , skates , rays , and relatives ) Vertebrates with jaws ; dermal and endochondral bone ab- sent ...
Page 343
... present are thin , overlap- ping plates of bone that continue to grow throughout life ; their lower jaws lack certain bones found in many chondros- teans or at least have some of these bones fused to single ele- ments ( see TELEOSTEI ) ...
... present are thin , overlap- ping plates of bone that continue to grow throughout life ; their lower jaws lack certain bones found in many chondros- teans or at least have some of these bones fused to single ele- ments ( see TELEOSTEI ) ...
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acid activity adaptation albite allegory analcime animals atoms bipolar cells birds bladder blood body called cause cells cellulose centimetres centre century changes chemical colour common cornea cotton countries currency disease effect electrical evidence evolution example excretion Existentialism Fabales fabrics falconiforms farm fascism fatigue Fatimid federal feldspar feldspathoids fencing ferns ferrite festivals fibres field filaments filtrate Finland fire fluid function gametophyte genera glands glomeruli groups important increase jute kidney Lake Eyre layer light magnetic marriage material membrane ment metres millimetres modern molecules movements muscle natural nerve normal occur optic organs percent plants plasma pressure produced properties protein renal result retina rhodopsin social sodium sorus species spinning sporangia spores structure surface temperature textile tion tissue tubule ture types United ureter urethra urine usually vision visual wool yarns