161 



marls, containing Am. Jamesoni, Am. Ibex, Am. Davcd, witli 

 tL.e lower portion of the beds containing Am. margaritahis, 

 whilst above the marls are brown crumbling Limestones, with 

 Am. margaritatus, Am. spinatus, and nmnerous specimens of 

 Gryphcea cymbium. We shall find this to be the same condition 

 of things prevailing in the vicinity of Cheltenham ; in the 

 many exposures of the Middle Lias beds along the western 

 escarpment of the Cotteswold Hills ; and in the magnificent 

 sections along the Yorkshire coast in the north, and Dorsetshire 

 in the south. In Gloucestershire the Middle Lias admits of 

 a sub-division into five zones of life : these are in ascending 

 order — 1st, zone of Ammonites Jamesoni; 2nd, zone of Am. Ibex; 

 3rd, zone of Am. capricomus; 4th, zone of Am. margaritatus ; 

 6th, zone of Am. spinatus. 



1. — The zone of Am. Jamesoni is known to me only in a few 

 locahties in Gloucestershire. One of these (an old pit sunk deep 

 for brick earth in the environs of Cheltenham,) has furnished 

 fragments of a large Am. Jamesoni, Sow., and many of the 

 young forms of the same species, known as Am. Bronnii, Rom., 

 with Ehynchonella rimosa, von Buch. Am,. Jamesoni, Sow., is 

 found in Robin Hood's Bay, on the coast of Yorkshire, where 

 it is associated with Gryphcea obliquata, Sow. ; Pholadomya 

 decorata, Ag. ; Pinna folium,, and Am. Taylori, Sow. This zone 

 is likewise well developed in the Island of Pabba, near Skye, in 

 the Hebrides, if I may judge from the suite of fossils collected 

 therefrom by my friend Akch. Geikie, Esq., F.R.S., Director 

 of the Geological Survey of Scotland, who sent these specimens 

 to me for determination. The original type Ammonites Jamesoni, 

 Sow., came from the brown micaceous sandstone of Pabba 

 which represents these beds. 



2. — The zone of Ammonites Ibex is likewise found in the 

 neighbourhood of Cheltenham reposing on the preceding. The 

 bed consists of a yellowish coloured clay in which numerous 

 hard calcareous nodules are imbedded; in these we find Am. 

 Ibex, Quenst., Am,. Maugenesti, d'Orb, Am. Henleyi, Sow., Am. 

 hipunctatus, Rom., with several conchifera as Crenatula ventri- 

 cosa, Sow., Mytilv,s scalprum, Sow., Area elongata, Quenst., 

 N 2 



