Looks like they used Gilbert & Bacon on the mounts after Gilbert retired in 1886. Some info on this site:
http://broadway.cas.sc.edu/content/s...bert-and-bacon
I have had a few G & B boxing cabinets and was able to estimate the date on one in particular of Arthur Chambers. Based on the photo of his left hand. His middle finger was amputated in 1877. As well as the studio addresses etc...