FLOOE.] 
FOSSILS. 
27 
stone and Coal formations, having the body protected by rhomboidal 
scales, and provided with two back fins, as well as two anal fins. The 
specimens exliibited are chiefly from Scotland. 
The fourth family, the Saurolds (see compartments T to 11), contains 
fishes which exhibit both the uneven-lobed and the even-lobed structure 
of tail, and is divided accordingly into two minor groups : the Sauroids 
have conical teeth mixed with minute prickly teeth. The scales vary 
considerably in form. This family presents living examples in the Bony 
Pikes (Lepidosteus) of the rivers and lakes of North America, and in 
the Bichirs [Folypterus) of the Nile. The Sauroid family is represented 
by numerous extinct species ranging through nearly all geological 
strata down to the Devonian. 
The Ganoid family called " Lepidoids " (see compartments 12 to 19) 
liave the same rhomboidal scales as the Bony Pikes, but in general 
form they are shorter and have a greater vertical diameter ; the teeth 
are of one kind only, and of a more or less conical form. 
The last family of the fishes with ganoid scales is the Pijcnodonts, 
of which all the principal genera will be found in compartments 20 
and 21. Like the members of the preceding group, these fishes have 
a short, high, and compressed form. Their teeth are usually large, 
rounded, and with low crowns admirably fitted for crushing shell-fish. 
Many of the species are from the Jurassic (or Oolitic) rocks ; some are 
from the Chalk, and a few extend into the Tertiary formations, but 
there are no known living species. 
In the preceding two great divisions of Fishes many of the families 
of which they are composed are extinct, and a very large proportion of 
the species is confined to the geological strata beneath the Chalk, 
whilst those which now come under consideration belong entirely to 
the Chalk and Tertiary formations, and the families have living re- 
presentatives. They form two important sections — the Ctenolds and 
the Cycloids. The Ctenoids, which are distinguished by their scales 
being serrated, or finely notched at the free edge, are arranged in 
compartments 22 to 26 : the common Perch is a good example of this 
group. The Cycloids occupy the compartments 27 to 36. Their 
scales have the edges smooth. The Fishes of the Mackerel tribe 
(Scomber idee), of the Carp tribe (Cyprinidcc), of the Pikes {Esocidcs), 
and the Herrings (Clupeidce), may be noticed as forming the more 
important families of this division. 
ROOM III. 
Excepting the two Cases 7 and 11, the whole of the Wall Cases in 
this room are devoted to Reptilian remains ; and amongst them may 
be first noticed the Dinosmma, which group contains the largest ter- 
restrial species, such as the Iguanodon and Megalosaurus. In the 
Middle Case (No. 9), on the north side of the room, are arranged the 
remains of the gigantic Iguanodon : firstly, and in the centre, the 
large slab of Kentish rag from Mr. Bensted s quarry near Maidstone, 
containing a great portion of the skeleton of a young individual ; to 
