ZONE OF AMMONITES CAPRICORNUS. 



79 



specimens of that Ammonite collected at Pabba by Mr. Geikie^ in a brown, micaceous sand- 

 stone, and which have passed through my bands for determination. 



The original type of this Ammonite was collected by Sir R. Murchison from beds of 

 the same age in the adjacent Isle of Mull. 



In Dorsetshire this Ammonite is occasionally found ; I have not seen a specimen, nor 

 have I been able to determine its bed. 



8. The Zone of Ammonites Ibex. 



Synonyms. — " Ochraceous Lias," Murchison, ' Geol. of Cheltenham/ 2nd edit., 42. 

 "Die Schichten diQ^ Ammonites Ibex," Oppel, 'die Juraformation,' p. 122. " Upper marls, 

 pars," De la Beche, ' Geol. of Lyme Regis.' " Ibex-bed," Wright, ' Quart. Jour. Geol. Soc.,' 

 vol. xiv, p. 25. 



In the neighbourhood of Cheltenham this zone is often exposed, and from hard, 

 calcareous nodules, imbedded in a light-coloured clay, its characteristic Ammonites are 

 collected; these are Ammonites Ibex, Quenst., A. Maugenesti, d'Orb., and A. Henleyi, Sow., 

 A. hipunctatus, Rom., with several Conchifera, as Crenatula ventricosa. Sow., Mytilus 

 scalpriim, Sow., Area eJongata, Quenst., Pinna folium, Y. and B., Cardinia attenuata, Buck., 

 and many other undescribed forms. 



In Northamptonshire fine specimens of A. Ibex, Quenst., and A. bipmdatus, Rom., 

 have been collected near Watford. 



9. The Zone of Ammonites capeicornus. 



Synonyms. — "Lias Gamma (pars Davseikalk)," Quensfcedt, ' der Jura Uebersichstafel,' 

 p. 293. " Schiste d'Ethe," Dewalque, ' Lias de Luxembourg,' p. 55. " Die Schichten des 

 Ammonites Davai'' Oppel, ' Juraformation,' p. 126. " Daveei-bed," Wright, ' Quart. Jour. 

 Geol. Soc.,' vol. xiv, p. 25. 



This zone is very well developed in England ; and wherever the Middle Lias is 

 complete it is found beneath the marlstone, consisting of laminated clays, containing 

 micaceous particles, or the argile is richly charged with peroxide of iron, whilst in other 

 localities it is represented by a brown, micaceous sandstone. The irregular, stony bands 

 found in the clay usually contain a large assemblage of fossils. This zone is likewise 

 especially rich in the remains of Echinodermata, and claims our special interest on that 

 account. 



1 'Quart. Journ. of the Geol. Soc.,' vol. xiv, p. 28. 



