LIST OF ILLUSTRATIONS 



FIG. 



30. Rimella fissurella . 103 



31. Trivia avellana - - 105 



32. Fusus porrcctus - - 107 



33. Planorbis discus - - 108 



34. Gastropods - . - 114 



35. Gastropods _ 118 



36. Orthoceras - - - 125 



37. Nautilus albcnsis - - 127 



38. Nautilus excavatus - - 128 



39. Asteroceras obtusurn - - - - 131 



40. Tetramcroceras obovatum - - 137 



41. Cephalopod Coiling Cycle - 141 



42. Manticoceras aff. retrorsiun - - 152 



43. Manticoceras rliyncJiostoma - 153 



44. Gastrioceras carbonari u in - 155 



45. Apertural Margins of Cephalopoda - - 156 



46. Apertural Margins of Cephalopoda - - 158 



47. Septal Sutures of Early Ammonoidea - - 162 



48. Septal Sutures of Jurassic and Cretaceous Ammonoidea 164 



49. Whorl-shape in Ammonoidea - - 166 



50. Lunuloceras bright i - - 176 



51. Olcostephanus astieriaiius - 178 



52. Mortoniceras inflatum - - 180 



53. Belemnites - - 185 



54. Belemnites - 188 



55. Calymene blumenbachi - - 195 



56. Dalmanites caudatus - - 199 



57. Triarthrus becki - - - 201 



58. Trinucleus concentricus - - 203 



59. Trilobites - 208 



60. Cheirurus bimucronatus - 210 



61. Hypostomes of Various Trilobites - 211 



62. Lanarkia spinosa - 223 



63. Fish Teeth and Scales - - 224 



64. Tooth Structure - - 226 



65. Caudal Fins - 228 



66. Fins and Limbs - - . - 232 



