OK, I think this page better illustrates the kind of primers that dstryr has:
http://www.soldusa.com/rainworx/detail.asp?id=42730
Judging by what I've seen, that's a pretty early primer tin -- probably from the late 1870s or the early 1880s.
Lastly, those primers are, if they are identical to the ones shown in the link I provided at the top of this message, Berdan primers.
Most metallic shotshells manufactured in the United States prior to World War I were Berdan primed.