AT BLACK YEN-, NEAE LYME KEtMS. 



25 



Cyprina cuneaia (abundant). 

 Gervillia rostrata (abundant). 



CythercBa caperata 



Trigonia scabricula 



CucuUcea glabra 



C. fibrosa 



Exogyra 



Cardium prohoscideum (3 small 

 fragments). 



Fecten orbicularis ? 



P. qxdnquecostatus (fragment) 



Tiirritella gro/aulata 



Phasianella'2, sp 



Serpula. 

 Sipkonia ? 



The spot in which these occnrred was about 50 ft. above the spot 

 in the Gault where I obtained the other fossils, and in nearly a 

 straight vertical line above it. All my subsequent endeavours to 

 find another such nest of fossil remains proved futile; but its 

 occurrence is a remarkable comment upon the fragmentary character 

 of geological evidence. But for this little local alteration of the 

 matrix, affording conditions for preservation, and proving that it had 

 once been teeming with life, the rock might have been pronounced 

 altogether barren of organic remains. 



In this spot, then, 50 ft. apart vertically, are two very distinct hori- 

 zons. There is but one (possibly not even one) specific form in common. 

 That one would be Tarritella granulata; but the specimen from 

 the Gault-bed is too poor a one for exact determination. The fauna 

 of the upper bed is a much nearer approach to the Blackdown fauna 

 than that of the lower, and for this reason as well as from its position, is 

 probably its equivalent ; but the absence of some of the commonest 

 Blackdown forms is noticeable. Among the commonest Blackdown 

 forms is Pectimcidus itinbonatus, and the closely allied ioTm.P.sublcevis ; 

 these, however, at Blackdown are distinctive of rather high horizons. 

 One might therefore be justified in reasoning from this fact that the 

 upper Black- Ven bed might be the equivalent of the lower Black- 

 down. But joer contra in the Black- Yen bed we have a great 

 preponderance of Cgprina cuneata, which at Blackdown is distinctive 

 of a bed intermediate between the two Pectunculus -heds. 



The evidence, so far as it goes, seems to show alternation of specific 

 horizons. It would seem as if inosculations due to changing littoral 

 conditions occurred among the beds, as before suggested by Prof. 

 Seeley*, with certainly a general thinning- out to the westward. 

 Under such circumstances it is questionable if we shall ever be able 

 to subdivide the Cretaceous beds of the West of England into the 

 marked divisions of Gault and Upper Greeusand which are applic- 

 able to the beds to the eastward. The black Lima-par allela bed of 

 Black Yen is, however, clearly of lower horizon than the lowest of 

 the Blackdown beds ; for it thins out before reaching Sidmouth, and 

 apparently immediately underlies the Blackdown series. The 

 general thinning-out to the westward is very evident. Mr. Hudle- 

 ston has pointed out that the Lower Greensand has thinned out 

 eastward of the vale of Wardour, though, according to Mr. Etheridge, 

 there are some traces of it to be found in the more southerly beds at 

 Black Yen f. The Gault, as shown in the coast-section, evidently 



* Quart. Journ. Geol. Soc. vol. xxxviii. (1882), p. 92. 

 t Ibid. p. m. 



