You can contact gdscentral.com and explain that is your image that is hosted on their machine. They may remove it or may contact the renter of the space and let him know. If he wasn't trying to sell the snake protrayed in the image or using it to gain anything (prestige or anything) then it may be more work than it's worth to get it removed. Why not just post underneath it "Great job posting pics [since you said it was a pic posting test]. We have many more snakes just like the image you got at www.http://www.geocities.com/southamptonherps/Southampton_He/Page_1x.html ... " you get the jist. Turn it into a positive viral marketing tool instead of email someone (probably a ten year old kid <img src="http://www.faunaclassifieds.com/iB_html/non-cgi/emoticons/biggrin.gif" border="0" valign="absmiddle" alt='
'> ) and taking the chance of coming out looking like a sourpuss.
Another thing you may want to do is throw on your URL (find a shorter one <img src="http://www.faunaclassifieds.com/iB_html/non-cgi/emoticons/wink.gif" border="0" valign="absmiddle" alt='
'>  
as a unobtrusive watermark in your images. This will get the same viral marketing without all the work (even on the ones you don't find).