In the summer of 2008 when I was in Montreal for a few days, I collected some snail shells, which I later identified as Discus catskillensis, a species native to North America. There were, however, objections to my identification and knowledgeable readers proposed that the snails I had found were instead Discus rotundatus, a European species introduced to the U.S. and Canada.
After a long hiatus and with additional specimens collected last summer, I have now decided to pinpoint the identification of the Discus of Montreal for once and all.
I have at hand several lots of Discus species from museums that I will be comparing with the Montreal shells. Here are 2 lots of Discus rotundatus.
This one was collected in Sweden in July 1923 by someone named B. Sundler. Then it passed into the hands of R. Jackson before coming to the DMNH. I am not familiar with either of those names.
The 2nd lot is even older. It was apparently collected by a Mr. Schenk in Switzerland before joining the collection of Victor Sterki. Sterki (1846-1933) was born in Switzerland. So these shells may very well have been taken before Sterki emigrated to the U.S. in 1883.
Old museum shells with associated bits of papers that reveal the collectors names and locality data do have some nostalgic charm. Here is a related post.