From Richard Owen [7 August 1837]1
“The result of the dissection of the head of the Rhynchops, comparatively with that of the head of the duck, is not what you anticipated.2 The facial, or sensitive branches of the fifth pair of nerves, are very small; the third division in particular, is filamentary, and I have not been able to trace it beyond the soft integument at the angles of the mouth. After removing with care, the thin horny covering of the beak, I cannot perceive any trace of those nervous expansions which are so remarkable in the lamelli-rostral aquatic birds; and which in them supply the tooth-like process, and soft marginal covering of the mandibles. Nevertheless, when we remember how sensitive a hair is, through the nerve situated at its base, though without any in its substance, it would not be safe to deny altogether, a sensitive faculty in the beak of the Rhynchops.”
Dissected beak of Rhynchops shows no extensive innervation. But beak may nevertheless be a sensitive organ of touch as CD suggests.
Please cite as
Darwin Correspondence Project, “Letter no. 371,” accessed on 1 October 2016, http://www.darwinproject.ac.uk/DCP-LETT-371