168 W. D. Carr—On the Lincoln Lias. 
above each other on the south cliff is quite uniform, and proves 
there is no hard bed of any importance between, or it would have 
caused a recognizable feature. This disappearance of the Marlstone 
is the more remarkable as it is known at Leadenham about 10 miles 
to the south, though rather rapidly thinning out, and it occurs also at 
some distance north of Lincoln. 
The lower beds of this division of the Lias are not quite so purely 
argillaceous as the rest of the series; a few Brachiopods are found 
resting on the surface of the nodules and pressed between some of 
the more sandy clays. The full thickness of the Middle Lias is about 
fifty feet. Below is a list of fossils :— 
SauRIA— 
Ichthyosaurus, sp. 
Mo.ivusca = CEPHALOPODA— 
Ammonites capricornus (rare). 
A. margaritatus. 
A. spinatus. 
Belemnites, 1 or 2 sp. 
GASTEROPODA— 
Trochus imbricatus. 
CoNncHIFERA— 
Avicula cygnipes. 
Cardium multicostatum. 
Hippopodium ponderosum. 
ConcHIFERA—continued. 
Pecten equivalvis. 
Pleuromya unioides. 
BRACHIOPODA— 
Lingula sp. 
Rhynchonella caleicostata. 
Waldheimia sarthacensis. 
ARTICULATA = CRUSTACEA— 
Glyphea. 
ANNULOIDA = EcHINODERMATA— 
Pentacrinus. 
PLANTEZ— 
(Wood). 
The only exposures of Lower Lias seen near Lincoln belong 
quite to the top of the series, and are entirely in the zone of 
Ammonites capricornus. These beds are well seen in the pit last 
mentioned underlying the Middle Lias, and consist of bright-blue 
shale with bands of nodules; these beds are difficult to distinguish 
from the Upper Lias, the nodules being also very similar. These 
latter, however, are unfossiliferous with the exception of an occasional 
A. capricornus or Belemnite sticking to the outside; the fossils are 
chiefly found in the Ostrea bands, or resting on the nodules, but not 
attached to them. Trochus imbricatus and Modiola scalprum are found 
throughout. About 80 feet of these beds are seen in the pit of the 
Bracebridge Brick Co., and about twelve additional feet in a pit 
a mile and a half further south, near Waddington Station; these 
latter are evidently lower in the series. Here the characteristic 
Ammonite is very abundant, and occasionally reaches a large size, 
with very strong ribs; other fossils are not very abundant excepting 
Oysters and Belemnites. Two well-known Lower Lias genera are 
altogether missing, namely, Gryphea and Cardinia, bands of the 
normal form of Oyster take the place (at this horizon) of the usual 
Gryphea bands. 
Fossils from the zone of Ammonites capricornus :— 
SavRia— 
Ichthyosaurus, sp. 
Plesiosaurus, sp. 
Mo.xivsca = CEPHALOPODA— 
Ammonites capricornus (common) 
A. defossus. 
A. Henleyi. 
Mo.ivusca—continued. 
A. spinatus (rare). 
Belemnites clavatus. 
B. (One or two other species, ) 
GASTEROPODA— 
Dentalium, sp. 
Trochus tmbricatus. 
