Charles Darwin's autograph and the date 1845 are seen below 4 portraits of finches. This is from his seminal work on evolution and shows how the beaks of finches differ as a means to survive in different environments. An accurate rendition of the original drawing.
Meaning of this tattoo: most definately its wearer is a fan of science, logic, the scientific method and evolutionary theory. Certainly not some bible-thumper.