The Inhabitants of the Aquarium 219 



The Turtles, Testudinata, interest us espe- 

 cially as inhabitants for larger aquariums. 

 Their most peculiar characteristic is that 

 they carry their bones, or by far the greater 

 part of them, on the outside of their bodies. 

 They are transformed into a case consisting 

 of an upper shell, the carapace, and a 

 lower shell, the plastron. In some turtles 

 the two are joined by a strong bony con- 

 necting piece, so that they are absolutely 

 rigid; in others, part of the soft body sepa- 

 rates the two shells, in which case the plas- 

 tron is movable so that the animal can draw 

 it up close to the carapace, hiding com- 

 pletely between the two. There is still a 

 third arrangement in which the plastron is 

 divided in two parts, so that it can be drawn 

 up, both in front and in the rear, enclosing 

 all parts of the turtle within its protecting 

 confines. The bony shell has a horny cov- 

 ering which in some species bears markings 

 of different colors. 



The eggs of the turtle are round and have 



