Page:The Zoologist, 4th series, vol 5 (1901).djvu/351

Rh disposal was restricted to a few badly preserved specimens." The importance of a clear comprehension of animal sense cognitions when a theory like that of mimicry is propounded must be obvious. Take, for instance, a bird and a protectively coloured caterpillar, such as it appears to our cognitions. Should the power of vision in the bird be in excess of that possessed by ourselves, the resemblance may be only superficial and powerless; should it be less, then the protection may be excessive—an idea almost unthinkable in the light of the doctrine of natural selection. We may see what appears to be, and may be, wonderful assimilative colouration or mimicking disguise, but the creature so protected, as it appears to us, may be readily detected by a keenness of scent in its enemies, of which we know little, or by a power of hearing, of which we know less. We certainly do not hear a tithe of the sounds produced by insects; the effect of some stridulating organs we can only comparatively estimate by their structural affinities to others of a more developed character, and which produce sounds capable of being recognized by our own sense of hearing. It is probable that many insect enemies discover their prey by sound alone. Other creatures find their food without apparently either sight or hearing. According to Jonathan Couch, the common Sea-hog or Sea-egg (Echinus esculenius), "though apparently destitute of every sense, or possibility of regarding external objects by sight or hearing, will travel up