J. F. SLAKE ON THE KIMMERIDGE CLAY OP ENGLAND. 215 



and this is by no means a full list. Those which have been recorded 

 by others in addition to these will appear in the table. 



The small oyster-bed Wo. 9 is less fossiliferous as regards species so 

 far as ascertained. They are as follows : — 



Ammonites biplex, Sow. 

 Belemnites nitidus, Dollf. 

 Turbo Julii, M. ? 

 Nucula, sp. 



Mactra tenuissima, Cont. 

 Trigonia, sp. 

 Pleuromya tellina, Ag. 



donacina, Ag. 



Thracia depressa, Sow. 

 Pecten midas, B Orb. 

 arcuatus, Sow. 



Pecten lens, Sow. ? 

 Avicula asdilignensis, Bla. 

 Modiola subeequiplicata, Goldf. 

 Exogyra nana, Sow. 



bruntrutana, Th. 



Ostrea deltoidea, Sow. 

 Ehynchonella inconstans, Sow. 

 Serpula intestinalis, Ph. 

 Cidaris Smitbii, Wr. 



, sp. (spine). 



Eryma Babeaui, Opp. 



On an examination of these lists, supplemented by other recorded 

 species, it will appear that out of 72 species found in these passage- 

 beds, while 29 are peculiar, and 13 are common to both formations, 

 there are 20 which pass up into true Kimmeridge Clay, and 10 which 

 come up from below, to which latter number it is probable that 

 some of the so-called peculiar forms really belong. It is well, how- 

 ever, to notice that the range upwards of Coral-Rag species is almost 

 confined to these beds, and that true Kimmeridge Clay has but very 

 little community of fauna with that formation. 



An almost exact repetition of this series in its lithological cha- 

 racters occurs on the west side of Ringstead Bay, and at Osmington 

 Mills, whence many fossils have been collected, but all of them of 

 species included in the above lists. Prof. Phillips records many of 

 these fossils and other Coral-Rag species from Wootton-Bassett 

 cutting, whence I also obtained in addition Trigonia Meriani, Bhyn- 

 chonella inconstans, Ostrea solitaria, Area mosensis, Serpula intesti- 

 nalis, and Lima pectiniformis. As this appears to be, in England, 

 the home of Rhynchonella inconstans, which occurs in higher zones 

 abroad, we must recognize these passage-beds by its presence at 

 Shotover and Eiley, and in Cambridgeshire. 



The peculiarity and abundance of the fossils of this zone, and the 

 easily distinguished character of the matrix, render it of consider- 

 able importance for the recognition of the junction of the two for- 

 mations ; and separated, as it is, from the Kimmeridge Clay proper, it 

 is a pity it has not received a more distinct recognition, but has 

 been mixed with a portion of the true Kimmeridge Clay to form 

 one region by Waagen. Amm. serratus has never occurred to me in 

 this zone ; nor is it recorded in the same bed with BhyncJwnella in- 

 constans by "Waagen himself, though they are associated by him as 

 characteristic fossils of the zone. I believe they occupy in England 

 different horizons, the latter being the most characteristic fossil of 

 these passage-beds. Ostrea deltoidea, which here occurs in layers, 

 occurs also in the Coral Rag in the same locality ; and a spine of 

 Cidaris florigemma was certainly in situ in these passage-beds. 

 Neither of these fossils, then, can be absolutely characteristic. 



But, with regard to community of fauna, I have been struck with 



