. A catalogue of the British non-parasitical worms in the collection of the British Museum. Worms. 8G ANNELIDES. flows {Glycera).—5. The brancliia is characterized more and more by the formation of a canal in communication with larger or smaller No. lacunae.—6. These branchiae may be distributed all along the body {Eunice sanguined).—7. They may be confined to a certain number of segments placed toAvards the middle of the body {Arenicola, Her- mella).—8. They may all be placed at the extremity of the body so as to form a double tuft (Serjmla)*." 8. Scalesf.—The scales are found only i
. A catalogue of the British non-parasitical worms in the collection of the British Museum. Worms. 8G ANNELIDES. flows {Glycera).—5. The brancliia is characterized more and more by the formation of a canal in communication with larger or smaller No. lacunae.—6. These branchiae may be distributed all along the body {Eunice sanguined).—7. They may be confined to a certain number of segments placed toAvards the middle of the body {Arenicola, Her- mella).—8. They may all be placed at the extremity of the body so as to form a double tuft (Serjmla)*." 8. Scalesf.—The scales are found only in a few genera. They have always a dorsal position, and seem to occupy the place of the superior pair of branchial appendages rather than the superior pair of cirri. Their texture is softish, and the margin is sometimes par- tially fringed with short filaments or fleshy cilia (No. XI. fig. 10«). In general the scales are placed over only such feet as are destitute of cirri, and alternate with these appendages,—an arrangement which has suggested the theory of their being modifications of the latter; but the genus Sigalion ofi'ers an exception, for here the two organs coexist on one and the same foot, and supplies a fact to disprove the opinion of their being the analogues of the superior cirrus. 9. Suckers.—There is no instance of a species of Polypodous Annelid with a sucker either at the anterior or posterior extremity. * Ann. & Mag. Nat. Hist. Ser. 2. ix. p. 155. See also Williams in lib. cit. xii. p. 393. t Called elytra by Savigny, whose nomenclature is followed by AudoiiiH and ,—but the term is very unsuitable. " Savigny is of opinion that cer- tain dorsal scales, in pairs, observable in two of the genera of his first family of Neri-ideans, are analogous to the elytra and wings of insects : this he infers from characters connected with their insertion, dorsal position, substance and structure, but not with tlieir uses and functions; for,
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