40 



65. Hamites, Parkinson, 1811 The shell at first straight, afterwards 



= Baculita, Fleming, 1828. curved, and next twice repeating the 



= Toxerites, Rafinesque, 1818. process ; the arrangement forming a 



species of compressed spiral ; the turns 

 not in contact ; Cretaceous. 



66. Hamullnta, D'Orbigny, 1850 The shell at first straight, afterwards 



curved, next straight, the turns not in 

 contact; Cretaceous. 



6. Shell forming a straight line. 



67. Bactlites, Lamarck, 1801 The shell slightly conical ; Cretaceous. 



= Homaloceratites, Hiipsch, 1781. 

 = Tiranites, Montfort, 1808. 

 = Baculita, Fleming, 1828. 



7. Shell spiral, not in the same plane. 



68. TrnRiLiTES, Lamarck, 1801 Turns of the shell spiral, in contact ; 



= Turrites, De Haan, 1825. Oolitic into Cretaceous. 



= Turrilithes „ „ 



69. Helicoceras, D'Orbigny, 1840 ... Turns of the shell spiral, not in contact; 



= Helicocerus, Xing, 1844. Oolitic into Cretaceous. 



8. Shell forming straight and curved lines, not in the same plane. 



70. Heteroceras, D'Orbigny, 1850 ... Turns of the shell at first spiral and in 



contact, not in the same plane, after- 

 wards tangentially divergent, finally 

 recurved and not in contact, and pro- 

 duced at a different angle to that of 

 the spiral ; Cretaceous. 



71. Anisoceras, Pictet, 1854 Turns of the shell at first spiral, not in the 



same plane, next tangentially divergent, 

 and finally recurved, none of the turns 

 in contact ; Oolitic into Cretaceous. 



