SUBORDER PLEURODIRA (TORTOISES)
FAMILY CHELIDAE (FRESHWATER TORTOISES)
Called terrapins in other countries, this particular family has species in Australia, New Guinea and South America.
These freshwater tortoises have well developed webbed feet, and can usually withdraw their heads into their shell.
Their shells are covered by well defined horny plates. Despite the high visibility of most species, many remain poorly known and undescribed, even on the heavily populated east coast of Australia. Like Sea Turtles, all species lay eggs, but the nature of the eggs laid varies, as do nesting habits between species, and even within geographical races of the same species.
No Australian species is threatened in any way, except for one species near Perth, Western Australia, in which less than 1000 individuals remain.
Current policies of the West Australian Government are ensuring the rapid extinction of that species, the Western Short Necked Tortoise Pseudemydura umbrina At least 16 species are currently recognised within Australia.
The above was from the book Australian Reptiles and Frogs by Raymond Hoser and now available on a fantastic CD-Rom along with a vast amount of other information, papers and the like on reptiles, frogs and other wildlife.