of Northamptonshire and Gloucestershire. 57 



here appears to be of no great thickness, and dijQFers materially 

 from that of the Cotteswolds. The hills which are occupied by 

 it near Blisworth are comparatively low, and form a striking 

 contrast to those in Gloucestershire partly composed of the same 

 formation. The fossils I obtained were a large Cardium, a Tri- 

 gonia, a Pecten, Terebratula, and a few Univalves. Fossils are 

 much more abundant at Northampton, though only occui-ring 

 there in the form of casts. 



Upper Lias. — From the position of the Inferior Oolite, the 

 Upper Lias was to be looked for at a low level at the base of 

 these hills, and I accordingly found it in a brick-pit in the 

 valley at Bugbrook between Weedon and Blisworth, below 

 the level of the Railway at no great distance from the Kilsby 

 tunnel. Beds of Lias clay and shale are used for brick-making 

 with the usual Upper Lias fossils, among which Ammonites 

 serpentinus and Belemnites were very prevalent. The clay is 

 traversed by a thin, continuous layer of limestone, which, as 

 I anticipated, turned out to be the ' fish bed,' identical litholo- 

 gically with the same band in Gloucestershire, and full of innu- 

 merable fragments of fish (though I could discover none entire) 

 and coprolites, with some specimens of Inoceramus dubius and 

 traces of Sepia. 



This 'fish bed' has been noticed by Mr. Morris in parts of 

 Lincolnshire and Northamptonshire on the Great Northern Rail- 

 way, and it is very probable that it will be detected in other 

 places where the Upper Lias occurs in situ, since it is rarely 

 wanting, in its course through Somersetshire and Gloucester- 

 shire, at the lower part of this deposit. In fact, this ' fish and 

 insect bed ' seems as persistent in the Upper Lias as the * Insect 

 limestone ' is in the lower. 



The section at Bugbrook is as follows in descending order : — 



ft. in. 



1 . Rubbly white limestone in detached bits, in dark blue shale, with \a q 



numerous fragments of Ammonites J 



2. Thin-bedded limestone (' fish bed ') ; white externally, inside has ^ 



a green tinge with white specks ; it has a laminated fracture, \n. o 

 and splits readily when weathered ; it does not occur in nodules, ( 

 but in a regular thin band in the clay J 



3. Thin, coarse, dark-colom-ed slaty stone, very rough, covered 



with spines, teeth and plates of Echinoderms, resting on the 

 marlstone. 



The thickness of the Upper Lias visible at this spot did not 

 exceed a few feet; it' is succeeded by the Marlstone with the 

 usual fossils. I could not determine the total thickness of the 

 Upper Lias, as there was no section exposed, but there must be a 

 considerable mass of clay between the Inferior Oolite and the 

 small section at Bugbrook, though probably not half so thick as 



