Sir J. Emerson Tennent, writing in _Notes and Queries_ (vol. viii. p. 223), referring to Porta's _Natural Magic_ for the vulgar error that not only in Scotland, but in the river Thames, "there is a kind of shell-fish which get out of their shells and grow to be ducks, or such-like birds," observes that this tradition is very ancient, Porta, the author, having died in 1515. In _Hudibras_ is an allusion to those-- "Who from the most refin'd of saints, As naturally grow miscreants, As _barnacles_ turn Soland geese, In th' islands of the Orcades." The story (says Sir James) has its origin in the peculiar formation of the little mollusc which inhabits the multivalve shell, the _Pentalasmi Anatifera_, which by a fleshy peduncle attaches itself by one end to the bottoms of ships or floating timber, whilst from the other there protrudes a bunch of curling and fringe-like cirrhi, by the agitation of which it attracts and collects its food. These cirrhi so much resemble feathers, as to have suggested the leading idea of a bird's tail; and hence the construction of the remainder of the fable, which is given with grave minuteness in _The Herball, or General Historie of Plants_, gathered by John Gerarde, Master in Chirurgie (London, 1597). After quoting the account, Sir James adds, that Gerarde, who is doubtless Butler's authority, says elsewhere, "that in the north parts of Scotland, and the islands called Orcades, there are certain trees whereon these tree geese and barnacles abound." The conversion of the fish into a bird, however fabulous, would be scarcely more astounding than the metamorphosis which it actually undergoes, the young of the little animal having no feature to identify it with its final development. In its early stage (see Carpenter's _Physiology_, i. 52) it has a form not unlike that of the crab, "possessing eyes and powers of free motion: but afterwards becoming fixed to one spot for the remainder of its life, it loses its eyes, and forms a shell, which, though composed of various pieces, has nothing in common with the jointed shell of the crab." Mr. T. J. Buckton (_Notes and Queries_, vol. viii. p. 224) says that Drayton (1613), in his _Polyolbion_, p. iii., in connexion with the river Dee, speaks of-- "Th' anatomised fish, and fowls from planchers sprung,"