86 



ANNELIDES. 



flows (Glycera). — 5. The branchia is characterized more and more 

 by the formation of a canal in communication with larger or smaller 



No.X. 



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 towards the middle of the body {Arenicola, Her- 

 melld). — 8. They may all be placed at the extremity of the body 

 so as to form a double tuft {Serpuld)* .""^ 



8. Scales f. — 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. tig. 10 a). 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 ofl^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 Audouin and 

 M.-Edwards, — 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 

 Nereideans, 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 their uses and functions ; for, as he also states, they are evidently 

 a species of vesicle, communicating by a pedicle with the interior of the body, 

 which, in the laying season, is filled with eggs, a circumstance in which they agree 

 with the egg-pouches of the Entomostracans ; and, therefore, Baron Cuvier's 

 opinion, that there is little foundation for the apphcation of this term to these 

 organs, seems to me correct." — Kirby's Bridgew. Treat, ii. p. 145. 



