> I'm trying to find the following paper: > Heard, William H. 1965. Comparative life histories of North American pill > clams (Sphaeriidae: Pisidium). Malacologia, 2: 381-411. Malacologia is online at BHL: http://www.biodiversitylibrary.org/bibliography/12920 Volume 2: http://www.biodiversitylibrary.org/item/47249 Francisco