What is the name of this Venetian pastry?
Those are Pan Pistacchio - this blog entry (not mine) has a picture of a sign in a shop window identifying them. It goes on to say that the general category of these buns is Fishermans Buns or Pan del Pescatore and that the green ones specifically are pistachio, which matches what I saw in Venice myself - the pistachio ones were always green and there were often other flavours next to them.

That should be enough to get you more pictures and recipes. I found some at this TripAdvisor page, but you can experiment.