Flatworms - Tasmanoplana tasmaniana

Darwin collected some terrestrial flatworms during his visit to Hobart.The only terrestrial Tasmanian animal formally named by Darwin was the flatworm now known as Tasmanoplana tasmaniana (Darwin). This was a new species which he described in 1844. It is still commonly found in forests around Hobart. His notebook gives a detailed account of the regeneration of specimens which he cut in half and of their aversion to light.

Geoplana typhlops - Tasmanian flatworm specimen from University of Tasmania Museum of Zoology

Links:

Flatworm notes from Charles Darwin's Zoology Notes and Specimen Lists from H.M.S. Beagle. by Charles Darwin and Richard Keynes.

Tasmanoplana tasmaniana - locations