268 SERPULID^. 



double pedal processes. The lower portion of each process forms a 

 mere transverse ridge, beset with the peculiar hooks to be described 

 by-and-by ; the upper process, on the other hand, is conical, and is 

 provided with elongated setae. The most striking feature of the 

 thorax, however, consists in the peculiar membranous expansion, 

 which, arising as a ridge upon each side of what might be termed 

 the nuchal surface of the animal, and attached to the sides of the 

 thorax, above the bases of the feet, runs down to terminate on the 

 ventral surface, behind the last pair of thoracic appendages. From 

 this origin it extends as a wide free membrane beyond the setae, 

 forming an elegant collar around the head, on whose ventral surface 

 the expansions of each side unite, and form a wide reflexed lobe, 

 while posteriorly they remain separate. To the thorax succeeds 

 what may be called the abdomen, which is much longer than the 

 other regions of the body ; and is, besides, distinguished from them 

 by the imperfect development of the feet, and the paucity of the setae 

 and hooks. In this, and in the caudal portion of the body, the 

 relative position of the hooks and setae is the reverse of what it is in 

 the thorax, the former being superior, and the latter inferior. The 

 caudal portion of the body is short, and wider than the abdomen. 

 Its rings are close-set, with well-developed hooks and setae ; and it is 

 terminated by two conical papillae, between which the anus is situated. 

 There are not less than fifty rings in the whole body." — Huxley. 



46. SERPULA. 



Serpiila, Linn, Syst. xii. 1264. Savign. Syst. Annel. 68 & 71 • Grube, 



Fam. Annel. 90. 

 Les Serpules, Ctiv. Reg. Anim. iii. 190. 

 Les Serpulees, Lam. Anim. s. Vert. v. 357. 

 Serpulsea, Latreille, Fam. Nat. 242. 



Char. Body elongated, narrowed backwards, of numerous segments 

 less distinct above than underneath, and crowded more and more as 

 they near the vent, which is small and not protuberant : first seg- 

 ment truncated obliquely for the insertion of the branchiae, thin and 

 dilated on its front margin ; the six following segments thoracic, with 

 a free undulated membrane along each side, folding towards the 

 back, and armed with six pairs of equidistant setigerous feet, and a 

 lesser pair in front, a little wider apart and more dorsad in position. 

 Head crowned with the plumose branchiae in two corresponding 

 erect fan-shaped tufts, with filaments ciliated on one side, and divided 

 by faint dissepiments like a Conferva : teutacula two, placed at the 

 base and between the branchiae, one of them dilated into an opercu- 

 lum : mouth anterior, between the branchiae, transverse, with plaited 

 equal lips and no teutacula : thoracic feet with a dorsal branch fur- 

 nished with acicular bristles, and a ventral series of uncini ; but the 

 first pair has not the uncini : abdominal feet similar to the thoracic. 



