Some consider the Ritchey card to be two variations one with the "Dove" and one without however the "Dove" is part of the original design and it is simply a matter of the dark green ink application and how well it shows.
If you look at these images you will see how the relation to the amount of dark green ink on the bottom of the cards coincides with the image of the "Dove" and the clouds in the sky. The more dark green and the higher it rises on the card, the darker the clouds and the more pronounced the "Dove."
The application of ink improved from the 150 series to the 350 series and therefore more "Doves" are seen on 350 series cards than 150 series. But it's there in all of them, just not seen in some.
