1859.] wsa&BX — ln'.feriok ooliie. 17 



No. 4. Another ferruginous sand-rock appears below the latter, 

 which contains seams with fossil shells. In these I observed Tn- 

 gonia, Astarte, and Nermcsa. It measures about 5 feet, and is under- 

 lain by 



No. 5. A yellowish sandstone, in which I found seams of small 

 rounded pebbles, lying at the bottom of the bed. The pebbly con- 

 glomerates arc about four inches in thickness, and occur at intervals. 

 I observed in the upper part some fragments of Belemnites, a Ceri- 

 thium, and a small shell resembling an Avicula. The bed measures 

 about 5 feet in thickness, and appears to be the lowest of the In- 

 ferior Oolite. Those which follow between No. 5 and the Alum- 

 whale, I refer to the zone of Ammonites Jurensis*. 



2. The Zone of Ammonites HuiTPHRiEsiANUs. 



Synonyms. — " Inferior Oolite of Dundry Hill," Conybeare and 

 Phiilips, 1822, * Outlines,' p. 236 ; " Grey limestone, Bath or Great 

 Oolite," Phillips, < Geol. of York.' 1829, p. 149 ; « Zone of Ammo- 

 nites Humphriesianus," Wright, ' Monogr. on Brit. Ool. Echinodenns." 

 1856. 



Foreign Equivalents. — " Eisenrogenstein (part) und Walk-Erde 

 Gruppe," Fromherz, 1838, 'Die Jivraformation des Breisgaues,' 

 pp. 13-17 ; " Brauner Jura y und c ," Quenstedt, 1843, ' Flozgeb.' 

 ]). "i'.iS; "Calcaire ferrugineux," Terquem, 1855, 'Paleontol. du 

 Depart, dc la Moselle,' p. 25; "Blanc Kalke, Korallenschicht, 

 Giganteus-Thone, und Ostrecn-Kalk " (Quenstedt), Pfizenmayer, 

 • Zeitsch. Deut. geol. Gesellsch.' 1853, vol. v. tab. 16. (Oppel, p. 333.) 



Description. — The zone of Ammonites Hwmphriesianus forms an 

 important subdivision of the Inferior Oolite, and is characterized by 

 a fauna very rich in many species of Gasteropoda and Cephalopoda, 

 which are found in no other zone of life. 



The lithological composition of the fossiliferous beds, whether 

 examined in France, England, or Germany, is very uniform through- 

 out. Everywhere the calcareous matrix is freely strewed with 

 small oviform ferruginous particles, which impart an iron-shot cha- 

 racter bo the nick, — a physical feature bo well exemplified in the 

 oolites of Dundry and Yeovil, in England, and of Bayeux and l£ou- 

 tieis, in Fran* 



The best types of this zone in England are the Lower portion of 

 (he Oolites bo the section at Dundry Hill Dear Bristol, and the 

 sections seen in the extensive quarries near Yeovil and Sherborne, 

 Somerset, and Burton-Bradatoek and Ghideoek, Donet. The peon- 

 liar Lithalogica] character of some of the beds of this subdivision, 

 containing, a-> they do, ferruginous oolitic grains disseminated in a 

 brown mndstone, Led my Lamented friend the Late II. K. Strickland. 

 Esq., to consider the iron-shot oolite of Dundry as the equivalent of 



* It is (iangeroua to attempt thit I on without ■ guide; md 1 would 



sdrise geologists desir mining the looalftf to obtain tin- >. n 



Mr. Peter Cullen, of Scarborough, who poMeaaaaa moat accurate knowli 

 .ill the beda here exposed Without hie able assistance, I feel tl would 



1 i\.' been indifferently performed 



VOL. XVI. PABT I. C 



