442 



ME. J. r. JACKSOX OlS" 



[vol. Ixxviii, 



newer with older deposits, which may be perfectly * conformable,* 

 that a false appearance of transition results : and such pseudo- 

 sequences may give rise to very erroneous views as to the real 

 importance of formations such as the Junction-Bed or the 

 Inferior Oolite. 



I was unable to measure a satisfactory section in situ at Doghus 

 Cliff; but some blocks on the talus showed features of considerable 

 interest. Section IV (p. 441), which is taken from one of these 

 blocks, is important, in that it shows what Mr. Buckman c-onsiders 

 to be the ' Fleurotomaria Bed.' The ' marlstone ' here does not 

 appear to include any representative of the serrata bed. The 

 '• Pleiirotomaria Bed' (?) is impersistent — it is absent from the 

 great majority of the blocks on the talus. 



As an illustration of the remarkably A'ariable characters of the 

 Junction-Bed, the following section (Y) of another block on the 

 talus of Doo'hus Cliff is of some interest. 



Sectio>- Y 



-The Ju>'ciioy-BED, measueeb ix a Bloce ox 

 THE Talus below Doghus Cliff. 



Hemerae. 



LilU (■?). 



Strata and Pauna. 



Feet incites. 



K. 



JBifrons. 



S errata - 

 s-pinatum. 



White vubbly limestone, with ochreous nodules. 

 Worn midoceras aif. hifrons, Dactylioceras spp. ; 

 HhynclinneUa sp. 



[1763, 4994, 5279, 5308, micromorph Dactyloid.s 

 presenting the aspect of Ammonites dai/i Reynes; 

 5278, micromorph Dactvloid of Cceloceras aspect ; 

 1777, 4991, 5212 (2 examples), 5309, Sfohno- 

 rhynehia botJienJiam_ptonensis Walker.^ 



Very obscure parting. 

 L. Pinkish-yellow mottled limestone. Hildoceras 

 hifrons. 



Resting upon the markedly planed-off top of 

 P+R. Light-brown oolitic 'marlstone,' becoming rough 

 and conglomeratic towards the base. Man}- small 

 gastropods {Amherleya, Cerithium, Fleuroto- 

 maria, Trochns, etc.) near the top. SJiynchonella 

 acuta, JRh. spp., ZeiUeria cornuta. Spiriferina 

 sp., Serpidce, etc. 



[5155 (2 ex.), 5687, Sornceorhynchia acuta (large); 

 5163 (2 ex.), Sitdirhynchia sp. = Hhynclionella 

 /aZZa.r. (Deslongchamps) Walker, but presumably 

 new; 5360, Quadratirhynchia cf. crassimedia 

 S. B. ; 5686, StolmorliyncMa houcJiardi ; 5159, 

 Spiriferina oxygona Davidson non Deslong- 

 champs, cf. Sp. signensis Buvignier.] 



10 



Here t\\QfaJciferiim layer and the ' IBJeuroiomaria Bed ' (?) are 

 absent, while the serrata bed is present. The lower layer of the 

 ' marlstone ' appears to pass up into the serrata bed without any 

 break ; probably this false appearance of transition is due to a 

 mingling of matrices along the line of junction. 



Scattered about on the talus of Doghus Cliff are several large 

 slabs of (presumably) ' Upper Lias ' limestone, showing a worn 

 and pitted surface covered with the adherent valves of a small 

 species of Ostrea and, more rarely, a large cristate Serpida. JSTo 



