<!--- 
if (document.images) {

var miocene = new Image();
miocene.src = "images/next_miocene_off.gif"
var mioceneon = new Image();
mioceneon.src = "images/next_miocene_on.gif"

var oligocene = new Image();
oligocene.src = "images/next_oligocene_off.gif"
var oligoceneon = new Image();
oligoceneon.src = "images/next_oligocene_on.gif"

var eocene = new Image();
eocene.src = "images/next_eocene_off.gif"
var eoceneon = new Image();
eoceneon.src = "images/next_eocene_on.gif"

var next = new Image();
next.src = "images/next_but_off.gif"
var nexton = new Image();
nexton.src = "images/next_but_on.gif"

var cretaceous = new Image();
cretaceous.src = "images/next_cretaceous_off.gif"
var cretaceouson = new Image();
cretaceouson.src = "images/next_cretaceous_on.gif"

var jurassic = new Image();
jurassic.src = "images/next_jurassic_off.gif"
var jurassicon = new Image();
jurassicon.src = "images/next_jurassic_on.gif"

var devonian = new Image();
devonian.src = "images/next_devonian_off.gif"
var devonianon = new Image();
devonianon.src = "images/next_devonian_on.gif"

var permian = new Image();
permian.src = "images/next_permian_off.gif"
var permianon = new Image();
permianon.src = "images/next_permian_on.gif"


}

function imgon(name)  {
if (document.images){
document[name].src = eval(name + "on.src");}
}
function imgoff(name)  {
if (document.images){
document[name].src = eval(name + ".src");}
} 
//--->