210 REPORT — 1851. 



Coasts, are armed with an articulated seta, which is bi-edged, and some- 

 times serrated. In this species the foliaceous cirri are wanting. The sub- 

 genera Lycidice, Aglaura and CEnone, present, in the construction of the 

 mechanical constituents of the feet, examples of exquisite contrivance. 



The solid elements entering into the composition of the feet of Lycidice 

 Ninetta, occur under two varieties: the first is limited to the superior foot, 

 the second to the inferior ; the superior foot consisting of the branchia, a pro- 

 trusile foot from the end of which the setse proceed, and in the axis of which 

 they run freely under muscular agency. These setae are constructed for 

 rowing (fig. 33) ; they include two forms of oars ; the first having a flat- 

 tened blade-like shape, and that in which the expanded extremity is abruptly 

 cut across spade-like (fig. 33, a). These oars are capable, while in action, 

 of being turned upon their own axes, in other words, of being " feathered." 

 The terminal edge of the spade-like variety is minutely serrated, adapting it 

 for scraping when required. The setae of the inferior foot are quite dif- 

 ferently formed. They are composed of a long strong stem expanded at its 

 extremity, to which is attached a second piece bifid at its remote end, and 

 designed for hooking or fixing or anchoring the body, according to the me- 

 dium in which the animal may be moving. A ligament-like membrane ties 

 on one side this articulated piece to the shaft. It is not impossible that this 

 sort of joint may be the faint foreshadowing of the true articulations observed 

 in the members of Insects and Crustacea. The anatomist must not, how- 

 ever, misinterpret this statement. In the Annelids, as already stated, there 

 is no true articulated member; the pieces of the hard parts or setae are never 

 united together by joints properly so called. The setae, being in all cases 

 composed of a whalebone-like substance, remarkable for its elasticity and 

 tenacity, are readily modelled into innumerable forms without the necessity 

 of actual joints. In all cases the connected portion is continuous in sub- 

 stance with the supporting shaft. In some cases the weak point of union is 

 strengthened b(' a ligamentous membrane (jiever muscular), which is really 

 only a portion of the setae thinned off" into a membranous form. To such a 

 mechanism the word ' articulation,' in its correct anatomical sense, cannot 

 apply. 



Below the setiferous foot in Lycidice is observed two foliaceous blunt 

 cirri, useful in swimming and feeling. The author has discovered two or 

 three smaller species of Lycidice, in which the feet differ from the former in 

 the construction of the soft parts, retaining in the setae the same type of for- 

 mation, while the hooks present slight variations. 



The worm described by Savigny under the name oi Aglaura fulgida, oi 

 which no British specimen is known on our coast, exhibits the same type as 

 that of Lycidice in the organization of the appendages. 



CEnone maculata is a graceful and active worm. Its feet are formed at 

 once with a view to ready and vigorous locomotion through loose soil or 

 through water. Each foot is composed of two flat fleshy appendages, of 

 which one is dedicated to respiration, and the other to tactile and mechanical 

 purposes. The setae, which are placed intermediately, supported on a pro- 

 trusile base, consist of long shafts, the ends of which are curved upwards 

 and club-shaped, the under surface being deeply notched into hooks which 

 recurve (fig. 34). An elastic membrane is also at this end of each seta, the 

 object of which seems to be that of wiping and cleansing the hooks by 

 passing over their plane surface. This worm is capable of creeping over a 

 hard surface at a very rapid pace. Each opposite pair of feet constitute 

 for its supporting annular segment an independent mechanism for progres- 

 sion ; the posterior part of the body is not therefore dragged or drawn 



