84 



THE LIAS AMMONITES. 



At Markoldendorf,^ near Einbeck, in a similar exposure for ironstone, he found the above 

 strata with Aeg. armatmn, Aeg. Centaurus, Aeg. brevispina, Aeg. Jamesoni, Trochus Icevis, 

 Pholadoviga amhigua, Inoceramus ventricosus, Gryphcea ohligua, and many Brachiopods. 



Dr. Emerson^ states that the beds with Aeg. Centaurus in the Markoldendorf district 

 yield the richest ironstones in the Middle Lias, and that they alone afford that beautiful 

 granular oolitic structure which is absent from most of the other ironstone masses of that 

 region. In some parts the Cenfaurus-heds rest upon the £revispina-heds, and contain a 

 great number of Gasteropods. The following Mollusca were obtained by this author 

 from these ironstones. 



Fossils front, the Aegoceras Ceniaurus-heds at Hullersen. 



Lytoceras fimbriatum, Sow. 

 Aegoceras striatum, Rein. 



— Centaurus, d'Orb. 

 Phylloceras Loscombi, Sow. 



— Herbert!, 0pp. 

 Nautilus intermedius, Soiv. 

 Belemnites elongatus. Mill. 



— clavatus, Schloth. 

 Trochus laevis, Schloth. 



— Retbergi, Schlon. 



— Thetis, Gold/. 

 Pleurotomaria multicincta, Schliib. 



— tuberculato-costata, Miinst. 



— granosa, Schloth. 



— solarium, Koch. 



Phaslanella phasianoides, d'Orb. 

 Cemoria costata, Emerson. 



— punctata, Emerson. 

 Opis Carusensis, (VOrb. 

 Isocardia cingulata, Gold/. 

 Unicardium lanthe, d'Orb. 

 Nucula cordata. Gold/. 

 Leda subovalis, Gold/. 

 — Galathea, dOrb. 

 Inoceramus ventricosus. Sow. 

 Limea acuticosta, Goldf. 

 Pecten velatus, Goldf. 

 Spiriferina rostrata, Schloth. 

 Pentacrinus basaltiformis. Mill. 

 — nudus, Schlijn. 



In Swabia the three zones of the lower half of the Middle Lias — the Jamesoni, 

 Ibex, and Davcei beds — closely resemble each other, and are only distinguished by 

 the characteristic Ammonites they contain, most of their Gastropods and Lamelli- 

 branchs having a wider range in the beds than the Cephalopods, a stratigraphical 

 condition which we have seen to prevail in other zones of life. According to Dr. Oppel^ 

 the following section fairly represents the actual state of the lower half of the Middle 

 Lias of Swabia. 



1 ' Eisenstein des mittleren Lias im N.-W. Deutschland,' p. 496, 18G3. 



2 'Die Liasmulde v. Markoldendorf bei Einbeck,' p. 34, 1870. 



3 'Die Juraformation,' p. 123, 1856. 



