[139]

Feb. 2/71/

Auditory hairs of Crustaceans.

This fact almost proves that the power of discriminating different notes must be in some way useful or necessary for the [perception] to draw in sounds, which relate to the life of a crab - such as the movement of its prey or its enemies. That may have not been acquired for the sake of opening [illeg]. As far as accords & discords are concerned Helmholtz makes it clear why they first are agreeable & then later disagreeable. It may be perceived that there are physical grounds for certain successions of notes or rhythm than of note taken at hap-hazard being now agreeable to the ear.

[in margin:] V Vol 2 p. 333 & [illeg] crustacean