1g Mantellian Museum at Lewes. 
volume of the Linnean Transactions, and of which an account 
is given in Vol. IL. p. 332. of your Magazine. Vegetable re- 
mains in chalk are extremely 1 rare ; there e are, however, in this 
collection fine specimens of es in chalk, and in the centre 
of flints, and also various remains of marine plants in chalk. 
An Ammonite of large size, or rather the cast of one, is truly 
remarkable ; all vestige of the shell or animal matter appears 
to be destroyed, except the siphunculus which is entire, and 
surrounds the disk like a hor ny tube, the size of a goosequill. 
In the Naitilus, as is well known, the siphunculus passes 
through the centre of the chambers, but in Ammonites the 
siphunculus is on the outer border, it is, therefore, exceed- 
ingly difficult to conceive how it could have been preserv ed so 
entire in the above specimen. Perhaps it may be interest- 
ing to some of your readers to state, en passant, that it is 
now nearly ascertained, that the shells of Nadtili, and other 
multilocular-chambered shells, were not the habitation of the 
animal, as was generally believ ed; but the shell, whether straight 
or spiral, was placed within the animal, and performed the 
function of an air bladder. The animals being enabled by the 
siphunculus, or tube, which passes through the chambers, to 
exhaust them or fill them with water, they could thus rise 
from vast depths or descend at pleasure. The most in- 
teresting objects in Mr. Mantell’s museum are the fossils 
from the Sussex-beds beneath the chalk formation, which 
are altogether of a different character from those in the chalk 
and green sand. The Sussex-beds, comprising what has 
been called the Hastings-sand, and sandstone, and the Weald- 
clay, with the strata of iron-stone, and limestone, abound in 
vegetable impressions and lignite or wood coal. Many of the 
vegetables appear allied to ‘the ferns and palms, &c., of tro- 
pical climates, and prove the existence of dry land at or 
before the period when the strata that contain them were de- 
posited. Of these vegetable remains there are numerous fine 
specimens in this collection, comprising all the fossil species 
that have hitherto been discovered in Sussex. 
The shells in these beds are, with some exceptions, con- 
sidered to belong to animals living in fresh water; none of 
the chambered shells, which are so numerous in dine strata 
above or below the Sussex-beds, have been discovered in 
them: but the most convincing proof that the Sussex-beds 
were deposited in fresh water is the abundant remains of ter- 
restrial plants which they contain, and also the remains of 
large animals, evidently formed for walking on land: these 
remains render the museum of Mr. Mantell unique. In the 
strata of Tilgate Forest, near Cuckfield, the remains of four 
