THE MIDDLE LIAS OF NORTHAMPTONSHIRE. 
253 
The rock-bed is the great water-bearing bed of the county 
to the West and South-west of Northampton, and there are 
probably some hundreds of springs and wells in it used for 
domestic purposes. The making of wells has facilitated the 
examination of the rock in districts where it does not come to 
the surface. As I propose to devote a section entirely to the 
consideration of the water-bearing capabilities of this bed, it 
is not necessary for me to do more here than call attention to 
the remarkable uniformity of this characteristic of it. 
The thickness of the rock-bed varies very little, com¬ 
paratively, in the west and south-western parts of the county ; 
in most cases it is between 5 and 6 feet, but near Byfield 
about 11 feet. In the northern parts of the county it gets 
very thin, and may be absent altogether in some places. 
Sections of the rock-bed are numerous, so I have omitted 
giving the localities of the fossils. A more complete list of 
the fossils, too, will appear in the section dealing with the 
Palaeontology of the Middle Lias. 
Fossils. 
Ammonites spinatus. 
Ammonites Holandrei. 
Belemnites paxillosus , and others. 
Cryptcdma consobrina. 
Eucyclus concinnus. 
Pleurotomaria sp. (?) 
Actcconina Ibninsterensis. 
Ostrea submargaritacea. 
Ostrea sportella. 
Ostrea cymbium. 
Plica tula spinosa. 
Pecten cequivalvis. 
Pecten liasinus. 
Pecten dentatus. 
Pecten textorius. 
Rhinites Dared. 
Bed 
Lima punctata. 
Lima Hermanni. 
Macrodon liasinus. 
Astarte striato-sulcata. 
Ca rdinia concinna . 
Spiriferina oxygona. 
1 'ei'ebra tu la pun eta ta. 
Terebratula Edwardsi. 
Waldheimia indentcita. 
Wa Idheimia resupina ta. 
Rhynchonella tetrahedra. 
Rhynchonella tetrahedra , var. 
Northamptonensis. 
Aerpulm. 
Pentacrinus. 
“ A.” 
The Transition Bed. 
This bed in Northamptonshire is usually a rather thin 
band of gray, friable, sandy marl, passing upwards into a red 
sandy clay. The lower part only is fossiliferous, but that 
extremely so, though most of the fossils are small. The 
marl appears to be made up chiefly of rounded calcareous 
grains; it effervesces considerably with acids, and weathers 
