206 J. E. BLAKE ON THE KIMMERIDGE CLAY OF ENGLAND. 



we find among the remainder, first, the very species that gives its 

 name to the Astartian zone, Astarte supracorallina — and, again, 

 Corbula DesJiayesia and Nucula Menkii, the first of which is always, 

 and the second usually, characteristic of lower beds ; and these, with 

 Ceriihium crebrum, are the common fossils. The latter is a near 

 ally, if not a variety, of Cerithium limceforme (Rom.), which is also 

 characteristic of the lower beds. Thus, standing alone, these pits 

 seem to me to present a fauna comparable to the Lower and not to 

 the Middle Kimmeridge ; and if they are not to be separated from 

 the beds with Amm. serratus, the conclusion becomes more certain. 

 If these are Lower Kimmeridge, the rest, of course, are also, and 

 we need only a description, and not so particular a discussion of 

 their fossils. 



The next exposures of this upper portion are at the south side of 

 the Louth road at Market Basen, and at Hamilton Hill, near that 

 place. No clear section is here seen ; but a rather peculiar fauna is 

 found in the large septarian doggers scattered about, and which are 

 generally formed round large Ammonites, such as Amm. Berryeri. 

 Several series of such doggers, some more septarian than others, are 

 found in the various clay-pits. The fossils here are: — 



Ammonites Berryeri, Les. Avicula nummulina, Bla. 



■ ■ biplex, Sow. Bhynchonella pinguis, Rom. 



yo ?, D 1 Orb. Astarte supracorallina, _D' Orb. 



Nucula obliquata, Bla. 



In the cutting east of Brigg, at the most easterly portion, is seen 

 dark clay, which contains similar fossils to those at Horncastle, 

 viz. : — 



Rostellaria mosensis, Buv. Area reticulata, Bla. 



Ostrea dilatata, Sow. 

 Discina elevata, Bla. 

 Serpula intestinalis (?), Ph. 



Cerithium forticostatum, Bla. 

 Anatina minuta, Bla. 

 Exogyra nana, Sow. 

 Lingula ovalis, Sow. 



In the Wrawby cutting the beds are now too rotten to give much 

 chance of seeing fossils ; in the most easterly portion, however, 

 occurred Amm. biplex, Astarte supracorallina, Ceriihium crebrum, 

 Nucula Menkii, Serpula tetragona, and Pentacrinus, sp. 



The above exposures are in descending order ; and we see in them 

 the gradual introduction of species that occur more abundantly 

 below, though the region of Amm. serratus is not yet reached ; there 

 is, however, nothing in them that would justify their separation 

 from the beds below as Middle Kimmeridge. 



Yet they have a facies in common that may serve to separate 

 them as a subzone, namely the absence or rarity of Amm. serratus 

 and the presence of abundance of Rostellaria mosensis and Anatina 

 minuta. This latter character does not hold for the two pits men- 

 tioned near Market Basen, whose peculiar fossils prevent their 

 correlation ; but they are probably the lowest of all these. 



The beds above mentioned, in the "Wrawby cutting, are succeeded 

 by some thickness of very gypsiferous, but unfossiliferous, clays, the 

 joints of which weather yellow. The occurrence of gypsum in the 

 Kimmeridge clay is also mentioned by Prof. Phillips (' Geology of 



