( IS ) (Orthoceracece.) 



a. Contractions moderate. PI. 2, fig. 9. 



b. Contractions so deep that the septa are united by the siphon only and ap- 



pear as if strung together. PI. 2, fig. 12. 



6. Hippurites. Lam. Cor- 

 isu-coPiiE. Thomson. 



Thick, cylindrical or A siphon, a gutter in- Several large species 

 conical, with irregular sep- stead of a siphon, or both, in the older Secondary 

 ta traversing two longitu- Mountains. 

 dinal cylindrical projec- 

 tions adhering to one of 

 the sides ; mouth closed 

 by an operculum. PL 1, 

 fig. 21, 26,28, 31, 33. PL 

 2, fig. 18. 



a. Conical, more or less arched. PL 1, fig, 21. 



b, Batholites, Montf, Straight, cylindrical. 



7. Baculites. Faujas. Ha- 

 mites. Parkinson. 



Straight, cylindrical, a 

 litttle conical, fusiform, 

 hooked or bent, com- 

 pressed : septa transverse, 

 undulated at the mar- 

 gins. PL i\ fig. 17, 19. 

 PL 2, fig. 16. PL 3, fig. 

 18, 23. 



a. With a siphon at the outer edge of the chambers. 



b. Without . , 



Maastricht. In the 

 clay at Folks lone. In 

 the chalk at Hamsey and 

 at Norton. 



8. Turrilites. Montf. 



Spiral, turreted : with Septa pierced in their 

 chambers divided by si- disks, 

 nuous septa : the turns 

 contiguous, all visible : 

 mouth round. PL 1, fig. 

 16. 



Belemnites. 



St. Catherine's Mount 

 near Rouen. In the 

 green sand at Horning- 

 sham, Wilts. Hamsey 

 Marl Pit. 



According to M. Beudant, they have never been found in transition limestone, 

 or grey wache, but first appear in the argillaceous iron stone which alternates with 

 bituminous slate. The internal of the two testaceous cones is filled with a solid 

 substance, presenting either radiating fibres or conical beds enveloping each other, 

 and their bases corresponding with the edges of the septa of the interior cone : 

 this solid part is sometimes found alone; at others, the kernels of the chambers of 

 the interior cone or the alveoli are also met with. PI. 1 , fig. 9. Most frequently the al- 

 veoli and the chambers themselves have left no other traces than some projecting cir- 

 cles within the interior cone ; but we sometimes meet with the alveoli still piled on 

 one another, but detached from the double conical case which envelopes them. 

 The exterior cone has generally a notch on one side of the base continued in a longitu- 

 dinal furrow. Klein, in 1 734, was the first who considered the fusiform Belemnitesto 

 be spines of Echini, from the similar exterior form, and the radiation presented in 



