PLATE XVII. 



Fig. 

 ], 2. Pleurotomaria antrina, /Sc/^/o^/^em. Testiferous; natural size. Tun stall Hill. 



3, 4. Pleurotomaria Tunstallensis, King. Testiferous ; natural size Tunstall Hill. 



5. — — Magnified view of the apical whorls of a testiferous speci- 



men, showing spiral striae anH sutural plications. Tun- 

 stall Hill. 



6. — — Elongated variety, natural size ; testiferous. Tunstall Hill. 



7. 8. Pleurotomaria Linkiana, King. Rather enlarged ; testiferous. Humbleton Hill. 

 9. Pleurotomaria nodulosa. King. A little enlarged ; testiferous : a, the slit. Tun- 

 stall Hill. 



10, 11, 12. Euomphalus Permianus, Zif;?^. Thrice the natural size ; testiferous. Tun- 

 stall Hill. 



13. Nautilus Frieislebeni, Geinitz. Cast (natural size) showing external face of the 



outer whorl. Humbleton Hill. 



14. — — Lateral view of the last specimen : a, the siphonal sheath. 



15. — — Inner tace of the outer whorl of the same : a, the siphonal 



sheath. 



16. — — Longitudinal section (enlarged) of a testiferous specimen, 



showing the siphonal sheath {a) passing through the 

 septa. Humbleton Hill. 



17. Nautilus Bowerbankianus, King. Lateral aspect (natural size) of a testiferous 



specimen. Tunstall Hill. 



18. — — Posterior aspect of the last specimen. 



19. — — Anterior aspect of the same. 



20. — — Nucleal whorls (twice the natural size) showing a septum 



perforated by the siphonal sheath («). Tunstall Hill. 



21. Bairdia curta, J/'Cby. Cast; magnified nine times. Dorsal aspect ; valves united. 



Humbleton Hill. 



22. — — Lateral aspect of the same specimen ; right valve upwards. 



