I know that I've lost a sense of time when I prepare myself for posting D-letter stamps when in fact this sunday we're already on letter E lol. Despite this not being Darwin's day then, he is still considered to be the Father of the Evolution, and the stamp is issued by Correos del Ecuador :) The year is 2009, marking the bicentenary of Darwin's birth. This stamp also compelled me to read more about this guy, and it is really an interesting read! I wasn't aware that he was so young (only 22!) when he set off on the HMS Beagle survey voyage.
I have bought this stamp in a PO in Ecuador amazed by its size - here you can see it against a standard size envelope. Alas a trip to the Galapagos Islands remains an unfulfilled wish...
You can find more of the E-stamps posts here.