ZONE OF AMMONITES RARICOSTATUS. 



75 



species, kindly sent me in exchange, from the Royal Museum of Stuttgard, by Professor 

 Fraas which could not be distinguished from ours if they were not previously marked for 

 identification. 



Fossils of the Zone o/" Ammonites oxynotus. 



Ammonites oxynotus, Quenst. 



— bifer, Quenst. 



— lacunatus, Buch. 

 Nautilus striatus, Sow. 

 Belemnites acutus, Mill. 

 Pleurotomaria Anglica, Sow. 



Plicatula ventricosa, Miinst. 

 Modiola minima. Sow. 

 Area oxynoti, Wr., n. sp. 

 Leda Eomani, Oppel. 

 Acrosalenia minuta. Buck. 

 Muricated spines of Cidaris. 



6. The Zone of Ammonites raricostatus. 



Synonyms. — " Hippopodium-bed (in part)," Murchison's 'Geology of Cheltenham,' 

 2nd ed., by Buckman and Strickland, p. 44. " Raricostatenschicht," Fraas, ' Wiirttemb. 

 naturw. Jahreshefte,' 1847, pi. 3. " Raricostatenbank," Quenstedt, 1856, ' der Jura,' 

 p. 292. "Die Schichten des Ammonites raricostatus," Oppel, 1856, 'die Juraforma- 

 tion,' p. 56. " Raricostatus-bed," Wright, 'Quart. Jour. Geol. Soc.,' vol. xiv, p. 25. 

 " Zone of Ammonites raricostatus" Wright, 'Quart. Jour. Geol. Soc.,' vol. xvi, p. 407. 



The beds forming this zone are exposed in several brick-fields in the vicinity of 

 Cheltenham. They consist of dark-coloured clays, more or less impregnated with the 

 peroxide of iron. In an excavation recently made near Marie Hill, for the purpose of 

 obtaining clay to make bricks for the town-sewers, the following section was obtained. 

 The beds are enumerated in descending order. 



No. ft. in. 



1. Gryphcea-bed ; a hard, ferruginous clay, which broke into fragments, and contained 



a great many specimens of Grypticea ohliqiiata. Sow 3 ft. to 4 0 



2. Coral-band ; a thin seam of lightish-coloured, unctuous clay, containing a great 



many small, sessile Corals, Thecocyathus rugosus, Wr., most of which appeared to 



have been attached to the curved valves of the Gryphcece 1 in. to 0 1^ 



3. Sippopodium-bed ; a stiff, dark-coloured clay, in some parts ferruginous ; con- 



taining Cardmia Listeri, Sow., s.nd Hippopodium ponderosum, Sow., in consider- 

 able numbers from 8 ft. to 10 0 



4. Ammonite-bed ; a dark, ferruginous clay, containing selenite, with the peroxide and 



sulphuret of iron, and great numbers of a highly pyritic brood of Ammonites, 

 likewise Ain. raricostatus, Am. armatus, and the other species of the list 



I Not 

 ascertained. 



In the parish of Cleeve, near Cheltenham, the same beds were formerly worked for 



