William Healey Dall, (August 21, 1845 - March 27, 1927), was a great American naturalist and a prominent malacologist. ... Anatomy of a slug A slug from North Bend, WA Slugs are gastropod molluscs without shells or with very small internal shells, in contrast to snails, which have a prominent coiled shell. ... John Edward Gray. ... C. S. Rafinesque Constantine Samuel Rafinesque-Schmaltz (October 22, 1783-September 18, 1840) was a nineteenth-century polymath who led a chaotic life. ... C. S. Rafinesque Constantine Samuel Rafinesque-Schmaltz (October 22, 1783-September 18, 1840) was a nineteenth-century polymath who led a chaotic life. ... Johannes Thiele (1860 - 1935) was a German zoologist specialized in malacology. ... John Edward Gray. ... Johannes Thiele (1860 - 1935) was a German zoologist specialized in malacology. ...