84 



ANNELIDES. 



(fig. 1,/) that indicate the power and cruelty of the species. No 

 acephalous Annelid has jaws of such strength ; and few have any 

 organs of the kind. The proboscis is occasionally roughened with 

 small horny prickles collected into clusters (fig. 1), or clothed with 

 minute fleshy papillae ; and its orifice is either plain or encircled 

 with tentacles (fig. 2, h). 



5. Feet. — In the majority of Annelides there is a foot on each 

 side of every ring which is armed with bristles, and provided with 

 certain soft appendages to which the names of cirri, branchiae, and 

 scales have been applied*. 



The foot in general is composed of two parts or branches placed 

 one above the other. These branches are sometimes wide asunder, 

 and easily to be distinguished into a dorsal or superior (No. VIII. 

 figs. 3, 4, a), and a ventral or inferior branch {b) ; but sometimes, on 



No. VIII. 



the contrary, they are intimately united, and appear to have coalesced 

 in one (fig. 5)f . Each branch is provided with a brush of bristles 

 (figs. 3, 4, 5, c), which the animal can protrude considerably from 

 the outer or distal end. 



The bristles are of two kinds, — the subulate and the hooked. 



The subulate bristles are distinguished into bristles (festucse) 

 properly so called (figs. 3, 4, 5, c), and into aciculi or spines (d). 

 The former are either grouped in brush-like bundles or arranged in 

 a fan-like series : their shape and structure are very variable. The 

 spines are stouter than the bristles, always straight and needle-like, 

 and deeper coloured. There is only one to each brush of bristles, 

 and it is enveloped in a proper sheath. 



The hooked bristles (uncinuli, No. X. fig. 9 ^) are never met with 

 on the two branches of the same foot : they exist only in the Tubi- 

 coles, and their presence is always coincident with a head indistinctly 

 developed or obsolete. They are disposed in one or two series, and 

 occupy the margin of a transverse fold or of a slightly raised mamilla. 

 Their arrangement in a more or less oval ring has given occasion to 



* On the structure of the foot, see De Quatjefages in Ann. des Sc. Nat. x. 

 (1848) 51. 



t 1 prefer to call the divisions of the foot branches rather than oars, as Savigny 

 and Blainville call them ; for the Annelides " with reptile motion creep," and do 

 not swim except when placed in untoward circumstances. Oersted names the feet 

 " pinnaj," and each has its " pinna superior v. dorsalis," and its " pinna inferior v. 

 venti'alis." — Consp. Ann. Dan. p. 5. 



