Ajax Variable not being returned from JavaScript

I’m receiving the variable to JavaScript, but not getting it back in PHP, and I think Its not being coded correctly in the JavaScript:

function glitch_player_display(mix_name) {
		alert(mix_name);
		throb.start();
		jQuery.ajax({
			type: 'POST',
			url: ajaxglitch_playerajax.ajaxurl,
			data: {
				action: 'ajaxglitch_player_ajaxhandler',
				mix_name: mix_name
			},
			success: function(data, textStatus, XMLHttpRequest) {
			throb.stop();
				var showglitchplayer = '#showglitchplayer';
				jQuery(showglitchplayer).html('');
				jQuery(showglitchplayer).append(data);
			},
			error: function(MLHttpRequest, textStatus, errorThrown) {
				alert(errorThrown);
			}
		});
	}

This is the php:

function ajaxglitch_player_ajaxhandler($arguments){
	var_dump($arguments);
}

returns empty.