William Duppa Crotch FLS (1832–1903) was a British naturalist, specialising in Norwegian wildlife and in entomology, particularly Lepidoptera, Hemiptera and Coleoptera.
He died young of pulmonary disease, possibly exacerbated by working in Philadelphia during a harsh winter.
[14][13] Mari was originally from Norway, and was the daughter of Thor Svee of Vaage [Vågå].
[19][20][11] Crotch was an occasional correspondent with Charles Darwin, and in one letter to Darwin dated 10 April 1865 he indicated his support for a "theory of Atlantis" that America and Africa had once been joined by a land bridge which might account for the geographical distribution of species, compared with a competing Behring Strait land bridge theory that had been advanced by Asa Gray.
Crotch spent ten summers observing the habits of lemmings near his Norwegian home (its location was described by Crotch as in the Vaage Valley by a path to Heindaken), admitting he could barely escape them:During ten consecutive summers spent in Norway I have three times lived literally in the midst of the lemmings, and have even, though involuntarily, shared my bed with them; thus I am enabled to speak positively, so far, at least, as my observation extends.