J. F. BLAKE ON THE KIMMEEIDGE CLAY OF ENGLAND. 



207 



Oxford/ p. 325) ; and the beds of this mineral met with in the sub- 

 Wealden boring may possibly belong to the uppermost portion 

 of the formation. This is one gypsiferous zone ; there is another 

 below, seen at Hawkstead. 



Following on this, at the Wrawby-road bridge, are the clays with 

 Amm. serratus and associated fossils. We here reach the region 

 most interesting by its organic remains, which are in great variety 

 and tolerable abundance. Pits in this zone are numerous, though 

 not all containing the same fossils. 



At Wrawby occur the following : — 



Ammonites biplex, Sow. 



serratus, Sow. 



Tbracia depressa, Sow. 

 Lucina minuscula, Bla. 

 Anatina minuta, Bla. 



Astarte supracorallina, D' Orb. 

 Trigonia Juddiana, Lye. 

 Avicula sedilignensis, Bla. 

 Area reticulata, Bla. 

 Lingula ovalis, Sow. 



At Market Rasen, on the north side of the Louth road, is the pit 

 in this region which appears to be opened on its most fossiliferous 

 part ; and from this and another on the Walesby road, nearly on 

 the same horizon, but a little lower, have come most of the Lincoln- 

 shire Kimmeridge-clay fossils of late years. It is covered by a few 

 feet of sand redeposited from superjacent beds ; and then we have 

 17 feet of blue clay most fossiliferous towards the base, 6 inches 

 of septarian limestone, and blue clay 2 feet. The best fossils lie 

 nearest to the limestone, above and below, but not in any well- 

 marked horizons. The commonest, besides the Ammonites cymodoce, 

 decvpiens, and serratus, are the characteristic Astarte, a new species 

 of Cerithium, Nucula Menkii, and Thracia depressa. Ostrea del- 

 toidea, though present, is very rare, as is also Lingula ovalis. The 

 complete list, richer than from any other locality and containing 

 several new forms, is as follows : — 



Ichthyosaurus, sp. 

 Teleosaurus, sp. 

 Ammonites decipiens, Sow. 



mutabilis, Sow. 



? rotundus, Sow. 



cymodoce, I? Orb. 



Berryeri, Les. 



■- serratus, Sow. 



Belemnites nitidus, Dollf. 

 Cerithium crebrum, Bla. 

 — — forticostatum, Bla. 

 Rostellaria rasenensis, Bla. 

 Natica microscopica, Cont. 



punctulata, Bla. 



Tornatella secalina, Buv. 

 Neritopsis delphinula, 1)' Orb. 

 Dentalium Quenstedti, Bla. 

 Pholadidea abbreviata, Bla. 

 Area longipunctata, Bla. 



mosensis, Buv. 



reticulata, Bla. 



Lucina minuscula, Bla. 

 Astarte supracorallina, If Orb. 



Astarte Michaudiana, _D' Orb. 

 — — ovata, Sow. (small). 

 Nucula Menkii, Bom. 

 Leda lineata, Bla. 

 Corbula Deshayesia, Buv. 

 Anatina parvula, Et. 

 Trigonia Juddiana, Lye. 

 Thracia depressa, Sow. 

 Pholadomya gequalis, Sow. 

 Inoceramus expansus, Bla. 

 Cardium striatulum, Sow. 

 Pinna, sp. 

 Pecten Grenieri, Cont. 



demissus, Ph. 



Thurmanni, Cont. 



Anomia Dollfusii, Bla. 

 Ostrea deltoidea, Sow. 



monsbeliardensis, Cont. 



gibbosa, Les. 



Exogyra nana, Sow. 

 Terebratula Gesneri, Et. 

 Lingula ovalis, Sow. 

 Hoploparia, sp. 



