SECONDARY AND TERTIARY FOSSILS, 
147 
the Gault. Some of the Gault ammonites in Wall Case 11 still 
retain much of the original iridescence of their pearJy shells. 
Attention may be here directed to the line suite of fossils from 
the Greensand of Blackdown, in Devonshire, where the shells are 
preserved in chalcedonic silica, and to the fossils from the 
so-called Upper Greensand of Cambridge, where numerous 
derived fossils, rolled and fragmentary, occur in the workings 
for phospliatic nodules, improperly called “ coprolites,” at the 
base of the chalk. 
The fossils of the Chalk naturally claim, by their variety and 
beauty, a large space. Most of the mollusca are in the Flat 
Cases 50 to 54, while the sponges, echinoderms, cephalopods, 
Crustacea, &c., are displayed in Wall Cases 13 and 14 . Many of 
the large cretaceous ammonites are mounted in a glass case at 
the top of the stairs ; whilst a selection of cretaceous sponges is 
displayed in a Case (D) at the head of the staircase, where also 
will be found the Lycett collection of Cretaceous Trigonias. The 
vertebrata from the cretaceous rocks, including many interesting 
specimens of chalk fishes, are exhibited partly in the Wall Cases 
of Recess No. 3, and partly in an adjacent Table Case (E). The 
latter contains some beautiful examples of the crushing teeth of 
Ptychodus, a characteristic fish of the chalk seas, allied to the 
living Port Jackson shark, and having the floor and roof of the 
mouth covered with these teeth, as with a tesselated pavement. 
A case between the Recesses 15 and 16 contains a large series of 
Upper Greensand sponges, mounted in the positions in which 
they probably grew on the floor of the cretaceous sea. 
All rhe southern end of the Gallery is given up to illustrations 
of tertiary palaeontology. The beautiful Eocene mollusca will 
be found in the Flat Cases 54 to 56 and in the drawers below. 
Among the Eocene mollusca may be noted the marine fossils of 
the Thanet beds, the estuarine and fresh-water shells of the 
Woolwich and Reading series, and the marine mollusca of the 
London clay and of the Brackleshain and Barton beds. The 
gigantic Cerithiums, from the Brackleshain series, are conspicuous 
objects in Case 58. The flu vio -marine fauna of the Oligocene 
beds of the Hampshire coast and the Isle of Wight is represented 
in Flat Cases 61 to 63. 
Turning to the Wall Cases we find Eocene fossils occupying the 
greater part of Nos. 18 to 20 . Especially noteworthy are 
the specimens of Nautilus from the London clay, with the 
pearly lustre still perfect ; the numerous crustacean remains, more 
or less resembling the crabs and lobsters of the present day ; 
the plant-remains from Sheppey, chiefly nuts resembling those 
of the nipa palm, abundant in parts of India, the Phillipines 
and the Moluccas ; and the masses of wood, bored by the teredo, 
by no means uncommon in the London clay. Some plant- 
remains from the Bagshot leaf-beds of Alum Bay and Bourne- 
mouth are also exhibited in these cases, where likewise will 
