part 4] 



JUR.VSSIC CHE02fOLOGY, 



443 



^satisfactory evidence sufficient to date the non-sequence thus 

 indicated Avas observed, and the question must be left open to 

 future research. 



The clay which was noted as coming in beneath the ' marlstone ' 

 .at the eastern end of Down ClifL thickens rapidly under Doghus 

 Cliff, where a thickness of over 10 feet can be seen. The maxi- 

 mum is at Thorncombe Beacon, where the thickness of clay is not 

 less than 16, nor more than 20 feet. 



The ' marlstone ' attains its maximum thickness in the central 

 portion of the Thorncombe-Beacon cliff's; but, unfortunatel}'', owing 

 to the steepness of these cliffs, it can scarcely be reached in situ. 

 However, a ver}^ large recent slip has brought down to the shore 

 an abundance of blocks : these yield a rich fauna, and show most 

 -of the subdivisions of the Junction-Bed, with the exception of the 

 striafulum la3''er, which, as Mr. Buckman has pointed out,i is 

 probably absent from Thorncombe Beacon. Section YI shows 

 two layers N, N^ not previously noticed. 



Section VI — The JuNciioisr-BED, measueed in a. very laege Block on 

 THE Talus below the Central Portion oe Thorncombe Beacon. 



Hemerse. 



Falciferuiii. 



Pre- 



falciferum. 



Pre- 



falciferum, 



Strata and Fauna. Feet inches. 



M. Massive limestone, mottled greenish and pink. 

 Harpocevas falciferum, Belemnites sp. 



Transitional from 

 N. Earth}'' ferruginous seam. Sco'pocerasa])])., FJi^llo- 

 ceras sp., Fteria ' iacequivalvis,' Trapezium sp., 

 small gastropoda. 2-3 



[6220a, Ha rpocerato ides Icissliagi (?) Haug; 5219, 

 5220, FL. cf. kisslingi Haug, hut ver}'' finely 

 rihhed; 5169, a micromorph Fhylloceras, like 

 Ammonites calypso D'Orhignj^, ' Terr. Jurass.' 

 1845, pi. ex, hut with straighter constrictions and 

 a smaller umhilicus.J 



Obscure parting. 

 Ni. Hard, grejdsh-white, nodular, earthy limestone 

 with FLarpoceras spp. at the top of the hed. 

 The lower portion of the hed is a soft j-ellowish- 

 white rock with scattered oolitic grains, which 

 appears to pass imperceptibly into the earthy 

 limestone at the top. Rhijnchonella acuta (?) , 

 Rh. sp. in the lower portion. A laj^er of large 

 Felemnites spp. near the base. 3-5 



From the top of the bed : [5222, FLarpoceratoides ? 

 aW. fellenhergi Haug; 6221, Harpoceratoides? ^^.^ 



Very obscure parting. 

 Serrata. P. Finely oolitic, light-brown 'marlstone.' Falto- 



pleuroceras spiiiatum, large Ilarpoceras sp., 

 large Felemnites spp., Cevithium sp., Fleuro- 

 tomarics spp., Trochus sp., etc. ; Pseudopecten 

 cequivalvis ; • RliyncJioiiella acuta, Mli. furcil- 

 lata, Fh. serrata, Rh. ' tetraedra,' Rh. spp., 

 Terebrattila pimctata, Zeilleria spp., Spiri- 

 ferina sp. 



[5167, a brephoraorph of Faltopleuroceras cf. 

 spinatum (D'Orbigny), showing the coronate stage 

 strongly spined, before the advent of a carina; 

 5231, Harpoceratoid = BCarpoceras 7'adians 

 Wright, Mon. Lias Amm. (Pal. Soc. 1882) Ixxxi, 

 4-6. 



1 Q. J. G. S. vol. Ixvi (1910) p. 82. 

 Q. J. a. S. No. 312. 



2h 



