458 
sions of which only remaining, the genus of the shell cannot always 
be determined. Among the more perfectly preserved bivalves are 
several terebratulitce, particularly the shell whose curious internal 
structure is figured PI. XYI. Fig. 11 and 13, and which has been also 
mentioned and figured by Mr. Walcott in his descriptions, &c. of the 
petrifactions found near Bath, p. 22, Fig. 33. To this stratum I be- 
lieve the patellitce of Gloucestershire belong, and in different parts of 
the stratum are found belemnitce. 
Above these is a sand stratum, and in this is the limestone and 
grey slate strata of Stunsfield, Colley Weston, Chippenham, See. 
In this stratum, the discoidal echinitce abound, as well as the trigonitce 
and belemnitce. In this strata are also found pinnitce, crenatulitce , and 
the fiat fossil oyster. But the fossils which are here most abundant are 
the bufonitce, and other parts of the palates and the teeth of fishes. 
On these strata lies the rag-stone, which has been employed for 
most of the ancient well-preserved buildings in the eastern part of the 
island. This stone is formed of small bivalves, chiefly anomitce. 
Above this is a thick clay, on which is the limestone, called the 
Bedford limestone ; in which are found small gryphitce , belemnitce, 
ostreitce, pectinitce, minute crenatulitce, pinnitce, a few trigonitce, the un- 
commonly-marked bivalve PI. XIII. Fig. 16, and various other shells. 
Immediately over this is a stratum of clay called clunch clay, 
from the beds of clunch, a soft chalk-like stone, which is found towards 
the top of it. Ammonitce , large gryphitce, belemnitce, and various bivalves 
are found in this stratum. 
Above this is the Woburn sand, containing in its lower parts frag- 
ments of silicified wood. To this succeed several sand strata and 
clays, and in one of these a thin bed of the shelly limestone called 
Sussex marble. Above this is the Aylesbury limestone, containing 
large ammonites, gryphitee, See. 
Over this is disposed the chalk marl. The lower or hard chalk 
rests on the chalk marl, and acquires in different parts different degrees 
