Comment 1 for bug 159122

You have installed (most probably a downloaded .deb) libssl0.9.8 version 0.9.8c-4ubuntu0.2.
Since you don't seem to have the feisty-security or feisty-updates repository available in /etc/apt/sources.list, trying to install libssl-dev will install the latest available version from the feisty repository (0.9.8c-4build1) which is incompatible with the version of libssl installed.
You should either install the libssl from the feisty repository or install the libssl-dev from the feisty-updates or feisty-security repositories (the latter preferable if you want the security fixes).