174 PHYLLODOCID.K. 



rarely, biramous, similar to each other, with a dorsal and ventral 

 cirrus, the dorsal generally foliaceous and branchial : bristles slender, 

 compound : a spine to each ramus. 



Obs. The Phyllodoces are the most beautiful worms * among the 

 Nereides, and are readily distinguished by the series of compressed 

 foliaceous lamellae, originating immediately above the insertions of 

 the feet, which garnish the sides of the body. The peculiar office 

 of these organs is conjectured to be respiratory-)-, but they also aid 

 the animal in its progress through the water, for, following the 

 motions of the feet, and capable of being partially altered from a 

 horizontal to a perpendicular position, they act as a bank of oars, 

 and must be especially useful when the worm glides from a solid 

 surface, and finds itself unsupported in the water. Hence the species 

 are quick and lively, and swim with considerable ease;];. We have 

 found them buried occasionally in light sand between, tide-marks ; 

 but they principally reside in deeper water amid the roots of coral- 

 lines and the shells of mollusca and sedentary aunelidans§. The 

 body is much elongated and proportionably slender, composed of a 

 numerous succession of similar segments, narrowed gradually towards 

 each extremity, more especiall}^ towards the posterior, which is ter- 

 minated by two short fleshy styles. From the mouth is protruded 

 at will a large proboscis, divided into two rings by a fold sometimes 

 scarcely visible (PI. XVI. fig. 3) ; the under half on the whole rough- 

 ened with fleshy papillae arranged in rows, while a series of larger 

 papillae encircles the orifice. There seem to be two eyes only||, 

 occipital in position, and larger than in the allied genera. The front 

 of the head is armed with four small simple antennae ; and on each 

 side of the post-occipital ring there are two pairs of unequal tenta- 

 cular cirri, jointed at the base, and usually kept retroverted when 

 the creature is at rest. The feet are rather small, uniramous, fur- 

 nished with a single spine, and a brush of very elegant, slender 

 bristles, divided by a joint near the middle into two portions, of 

 which the terminal one is as sharp as the finest needle (fig. 6). 



In the Phyllodoces the blood is not red as in the great majority 

 of the Annelides, but yellowish or coloiirless^. 



* " Virgines pulcherrimse inter Nereides." — 0(ho Fabricius. 



t Cuv. Regn. Anim. iii. p. 202. It would be wrong to overlook their resem- 

 blance to the branchise in the larvae of the Ephemerides. See Reaumur, Hist, des 

 Insectes, vi. p. 468. pi. 45. f. 2. 



X " Currit egregie ; natare etiam valet lamellis suis retroversis oblique sursum 

 erectis." — Fabr. Faun. Groetil. p. 298. 



§ Audouin and M.-Edwards, Litt. de la France, i. p. 237. 



II According to Lamarck, four, " mats les posterieurs sont peu apparens." — 

 Anim. s. Vert. 2de edit. v. p. 556. 



\ Lam. Anim. s. Vert. 2de edit. v. p. 556. Ann. des So. nat. n. s. x. p. 197. See 

 also Williams, Rep. Brit. Assoc, p. 212. 



