Page:The Zoologist, 4th series, vol 3 (1899).djvu/385

Rh No specialist who works long at any large group of animal forms, especially at insects, can escape meeting with these problems. This is particularly discovered when, in monographing a family, species are found resembling insects belonging to another order. Thus, in recently working out some Hemiptera for the 'Biologia Centrali-Americana,' I found in the family Lygæidæ a species with all the superficial form and colour of an Earwig (Forficula) belonging to the order Orthoptera; while among the Lygæidæ and Capsidæ were many species which mimicked Ants (Hymenoptera). To add to the problem, Lygæidæ and Capsidæ were found mimicking one another. Dr. Thorell made a similar observation in monographing Burmese Spiders. Ligdus chelifer "is a small flat Spider belonging to the family Salticoidæ, and resembles very much a Cheloneth (Pseudoscorpion); Prolochus longiceps has some resemblance to an Orbitelarian Spider of the genus Meta (M. segmentata, f. inst.)." Now, in the first case, and, alluding to the writer's own experience, it appears we have "Suggested or Probable Mimicry," because we possess no knowledge whether these Hemiptera are found with the Earwigs and Ants they mimic, nor whether they are avoided or neglected by enemies because of this mimicry. We can only report that these insects are mimics one of another as seen in our cabinets, and that as nothing is, or can be, predicated as purposeless in nature, neither can these assimilative forms be meaningless; and, further, arguing from demonstrated knowledge in other cases of mimicry being protective, the presumptive evidence is that the theory of protection affords the clue to the origin of the mimetic guise of these insects. But this is only circumstantial evidence of the weakest description, and, though we may believe as a matter of biological faith, based on analogous cases in nature, that this is the explanation, it is probable, or more than probable, that the progress of science is retarded by confounding scientific suggestion with