This specimen was collected in the United States at the end of May in 1935 and is now held at the Australian National Herbarium in Canberra. To the lower right is part of the herbarium packet that holds the specimen. You can see numerous whitish "pinpricks" in the lichen thallus. They are the pseudocyphellae. The white cracks indicate damage to the thallus, probably by pressure for the whole specimen is fairly flat.
Originally this specimen was identified as Parmelia perlata by the collector (Stuart K. Harris) but as you can see that name has been crossed out and Cetrelia olivetorum written in pencil. Inside the packet there is a note that the specimen was re-identified as Cetrelia olivetorum in 1981 by the American lichenologist Clifford W. Wetmore.
Photographer: Heino Lepp