.
.
local $_; # always a good habit unless you know why don't want it
chdir $Dir;
opendir DIR, '.';
my (@dirs, @files);
for (readdir DIR) {
    next if /^\.\.?$/; # we don't want to catch the . and .. entries
    push @dirs, $_ if -d and not -l; # only non-symlink dirs please
    push @files, $_ if -f and /\.ext$/; # -f because it could be a directory or other non-file called "something.$ext"
}
closedir DIR;
.
.