182 THE OCEAN WORLD. 
calcareous, being fixed, simple, conical when young, and globular 
when old. The animals have lateral series of short tentacula around 
a distinct mouth; they are contained in shallow cells, meeting at the 
base, and forming by their union long and tortuous sulci. deandrina 
(Diploria) cerebriformis (Fig. 65), so called from its resemblance to 
the convolutions of the brain, is a native of the American Seas. 
Fig. 66.—Fungia echinata (Milne-Edwards). 
The genus /ungia, so called by Lamarck from the resemblance 
of the species to the vegetable Fungi, presents forms too remarkable 
in their appearance to be passed over in silence, All the species of 
this genus occur in a living state. Nevertheless some species of 
closely-allied genera are very numerous in the Cretaceous period. 
The genus, as we have already said, takes its name from its 
supposed resemblance to a Mushroom. “ But,” says Peyssonnel, 
“there is this difference between terrestrial and marine mushrooms— 
