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and they are scarcely if at all to be seen at four or five 
inches, the external measure of the original. I must observe 
that some other shells become the reverse or narrower and 
longer as they grow bigger, of which I shall hereafter show 
good examples, that may guard us agaist mistakes in fu- 
ture. A section through the middle is a curious geometrical 
object, and expresses this part of the subject clearly, for 
take any part of it as the younger shell it will show that it 
is longer than wide in proportion as it is smaller*, see the 
left hand figure. I have got a piece out of the inner part 
of the large one agreeing with it. The sections in this way 
often present beautiful specimens, of which I have one 
three inches in diameter; besides showing the different form 
of the infant shell, it shows the chambers becoming deeper 
and squarer, giving a new contour. The middle figure 
shows a front view of the septa in the young state, when 
they are broader in the middle. The right hand figure 
shows that the sides are become broader in the adult state, 
while it shows also the inner undulations and spreading rami- 
fications of the sutures, and the place of the siphunculus, 
which is often difficult to discover. I have, however, a 
specimen from Kellaways by favour of Mr. Salmon, where 
it is rendered conspicuous by a stain of oxide of Iron. I 
have marked the spot in the middle figure. The specimens 
are sometimes very beautifully filled in a variety of ways 
with crystallized Carbonate of Lime of various colours, and 
sometimes with granular grey or other coloured Limestone. 
The divisions of the chambers are sometimes distinct, and 
sometimes quite obliterated for two or three turns. I have 
called this species sublevis, as it is wrinkled with transverse 
furcate costa when young, but otherwise smooth and shining. 
Colonel Hardwicke has a fine specimen, said to be found in 
a bed of sand in digging a well at Wisbech. 
* More so than is generally the case with a volute. 
