One of the most interesting among the early observations of superficial resemblance between forms remote in the scale of classification was made by Darwin himself, as described in the following passage from his letter to Henslow, written from Monte Video, Aug. 15, 1832: Amongst the lower animals nothing has so much interested me as finding two species of elegantly coloured true planaria inhabiting the dewy forest!
"Darwin and Modern Science"
A.C. Seward and Others