CONTENTS. 



Preface vii-xi 



Law of Morphogenesis, viii. Organic Equivalence, viii. Morphological Equiva- 

 lence, viii. Morphological Difference, ix. Acceleration in Development, ix. Gera- 

 tology, ix. Acceleration in Degeneration, x. The Three Phases of Development, x. 

 Law of Variation, x. Local Origin of Forms, xi. 



I. Introduction . , 1-53 



Origin and Characteristics of Suborders, 1-8. Nomenclature of the Stages of 

 Growth and Decline, 8-21. Theory of Radicals and Morphological Equivalence in 

 Progressive Forms, 21-28; in Retrogressive Forms, 28-40. Law of Acceleration, 

 40-48. Origin of Differentials, 48-53. 



II. Genealogy 54-70 



General Remarks, 54-56. Radical Stock, 57. Plicatus Stock, 57-62. "Wsehnero- 

 ceran Series, 57. Schlotheimian Series, 57, 58. Caloceran Series, 58-61. Vermi- 

 ceran Series, 61, 62. Levis Stock, 62-70. Amioceran Series, 62, 63. Coroniceran 

 Series, 63-65. Agassiceran Series, 65, 66. Asteroceran Series, 66-68. Oxynoticeran 

 Series, 69, 70. Incerta Sedes, 70, note. 



III. Genesis of Characteristics 71-84 



Anagenesis, or the Genesis of Progressive Characteristics, 71-74. Catagenesis, or 

 the Genesis of Retrogressive Characteristics, 74-80. Differential Characteristics 

 80-84. 



IV. Geological and Fatjnal Relations 85-119 



Remarks, 85-89. Psiloceras and Caloceras, 89-93. Waehneroceras and Schlotheimia, 

 93-95. Vermiceras, 95, 96. Arnioceras, 96, 97. Coroniceras, 97-99. Agassiceras, 

 99, 100. Asteroceras, 100, 101. Oxynoticeras, 101-103. Fauna of South Germany, 

 Table I., 103. Fauna of the Cote d'Or, Table II., 103, 104. Fauna of the Rhone 

 Basin, Table III., 104-106. Fauna of England, Table IV., 106. Fauna of the Prov- 

 ince of Central Europe, Table V., 106-108. Fauna of the Province of the Mediter- 

 ranean, Table VI., 108-112. Summary, 112-119. 



V. Descriptions of Genera and Species of Arietidjs 120-221 



Radical Stock, 120-125. First, or Psiloceran Branch, 120-125. Psiloceras, 120- 

 124. Tmaegoceras, 125. Plicatus Stock, 125-161. Second, or Schlotheimian Branch. 

 125-136. Wsehneroceras, 125-127. Schlotheimia, 127, 128. Third, or Vermiceran 

 Branch, 136-161. Caloceras, 136-154. Vermiceras, 154-161. Levis Stock, 161-221. 

 Fourth, or Coroniceran Branch, 161-194. Arnioceras, 161-174. Coroniceras, 174-194. 

 Fifth, or Agassiceran Branch, 194-214. Agassiceras, 194-200. Asteroceras, 200-214. 

 Sixth, or Oxynoticeran Branch, 214-221. Oxynoticeras, 214-221. 



Index 



223 



