THE CEPHALOPODA. 



195 



canal. Septa formed of lobes and saddles divided into single parts. Siphonal lobe 

 shorter than the superior lateral lobe. Hoplites falcatus, Mantel) (fig. 76), from the 

 Chalk Marl, and H. auritus, Sow., from the Gault, are good types of Tuberculati. 



Fig. 76. — Hoplites falcutus, Mantell. 



Fig. 77. — ScMoenhaeliia Goupiliana, d'Orb. 



c. Sjjecies loith the siphonal urea trenchant iuithout forming a keel. 



5th Section. Clypeiformi, ct Orhigny. Shell compressed, generally smooth or little 

 ornamented with undulating folds or radii. Siphonal area sharply bevelled, without a keel. 

 Spire with large whorls mostly much involuted. Septa divided into a great number of 

 lobes formed of single parts, and of saddles partly in pairs and partly single. Siphonal 

 lobe shorter than the superior lateral lobe ; the saddles and the lobes large and short. 

 S. Goupiliana, d'Orb. (fig. 77), from the Upper Greensand, is a good type of this section. 



d. Species with the sijjJional area pirominent and crenulated on the viedian line. 

 6th Section. Amalthei, von Buch. See page 188. 



7th Section. Pdlchelli, d^Orhigny. /S//e// elegantly divided on the sides by promi- 

 nent ribs, straight and not flexed, which passing from one side to the other leave upon 



Fig. 78. — Hopliles Brottianus, d'Orb. 



Fig. 79. — Hoplites Deverianus, d'Orb. 



