> How to download a gallery that doesn't have an index page?>
<http://acertainhost/butterflies/[001-099].jpg>
> So I need to download images from 001 to 099. Is there a 
> simple way of asking HTT to do this job instead of typing 
> the 99 links?
There is no simple way. But the least complicated one is to 
create a text file, with one URL per line, and use the "URL 
list" feature of httrack.