12 Mantellian Museum at Lewes, 



volume of the Linnean Transactions, and of which an account 

 is given in 'Vol. II. p. 332. of your Magazine. Vegetable re- 

 mains in chalk are extremely rare ; there are, however, in this 

 collection fine specimens of wood 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 horny tube, the size of a goosequill. 

 In the Nautilus, 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 preserved 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 A^autili, and other 

 multilocular-chambered shells, were not the habitation of the 

 animal, as was generally believed; 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. MantelFs 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 the 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 



