MOLLUSCA. 619 



bilicated; volutions hidden, transversely and minutely striated and ribbed; 

 back acute. One inch and a half long. Fossil. 



10. Ammonites armatus.—The Armed Ammonites. Plate Ixxii. fig. 7. 

 Subcarnated, volutions depressed at their inner margins; with strong trans, 

 verse striae and clavate ribs. Fossil. 



11. Nautilus umbilicattis.—The Umbilicated Nautilus. Plate l.\xii. fig. 

 6. Suborbicular ; the centre of the volutions umbilicated ; aperture round, 

 heart-shaped ; pale fawn-coloured, with chestnut undulated transverse 

 clouds. Six inches long. Inhabits the Indian Ocean. 



12. Xummulites complaiiatits.— The Flat Nummulites. Plate Ixxii. fig. 9. 

 Orbicular, broad, depressed at the sides, and smooth ; margin undulated. 

 One inch and a half long. Fossil in France. 



13. Vorticialis strigilata. — The Creased Vorticialis. Plate Ixxii. fig. 10. 

 Somewhat depressed, transversely ribbed, and spirally striated. Fossil. 



14. Polystomella crispa. — The Wrinkled Polystomella. Plate Ixxii. fig'. 



11. Shell discoid, multilocular, with invisible volutions; with numerous 

 transverse ribs ; aperture formed by variously disposed holes. 



15. Siderolites calcitrapoides.— The Chalk Siderolites. Plate Ixxii. fig. 



12. With four lobes, and punctated throughout. Fossil in the mountain of 

 St Peter, at Maestricht. 



16. Discorbis visicularis. — The Visicular Discorbis. Plate Ixxii. fig. 13. 

 Volutions nodulous, subvisicular ; the internal volution hidden by the no- 

 dules. Fossil at Grignon. t 



17. Placentula astricans. — The Star-Shaped Placeutula. Plate Ixxii. fig. 

 14 Volutions convex ; partitions radiating from the centre. Fossil. 



18. Lenticulites rotulata. — The Rolled Lenticulites. Plate Ixxii. fig. 15. 

 Orbicular ; margin acute ; disc globular. Fossil at Mendon. 



19. RotuHtes trochidiformis. — The Trochus-Shaped Rotalites. Plate 

 Ixxiu fig. 16. Shell conoid; volutions carinated; loiver one granulated. 

 Fossil at Grignon. 



20. Melonites sp/usroidea. — The Round Melonia. Plate Ixxii. fig. 17. 

 Entirely globular. Fossil. 



21. Gyrogonites medicaginula.—Somewhsit 8plierical,with transverse keels, 

 and a spiral extremity. Fossil at Montmorency. 



22. Miliola ovata. — The Oval Miliola. Plate Ixxii. fig IS. Ovate, small. 

 Fossil at Grignon. 



23. Orbiculina uncinata. — The One Sinused Orbiculina. Plate Ixxii. fig. 

 9. Spirally striated, and the volutions separated by a deep sinus. Fossil. 



24. Cristellaria squammula. — The Scaled Cristellaria. Plate Ixxii. fig. 20. 

 Shell externally covered with minute scale-like marks. Fossil. 



25. Renulites opercularis. — The Lip-Shaped Renuluia. Plate Ixxii. fig. 

 21. Semilunar, flat, with arcuated concentric ridges. Fossil at Grignon. 



26. Lituolites nautiloidea.— The Nautilus-Shaped Lituola. Plate Ixxii. 

 fig. 22. Discoid, tailed, ribbed; septa with six perforations. Fossil at 

 Mendon. 



27. Spirolina clavata.— The Club.Shaped Spirolina. Plate Ixxii. fig. 2.1. 

 Club-shaped, spiral, smooth, ending in a lengthened erect body. Fossil. 



28. Spirula Peronii.—VeTou's Spirula. Plate Ixxii. fig. 24. Pale snl- 

 phur.yellovv, very fragile, horn-shaped ; diameter about one inch. Inhabits 

 the West Indian seas. 



