160 THE ANNELTDES. <§, 149. 



With the Dorsibranchiati, the many delicate threads which arise from 

 the cerebral ganglion by special roots and pass to the different portions of 

 the digestive canal with a ganglion here and there upon their course, may 

 be regarded as sphuichnic nerves. *'^^ 



With the Aniphinomae, Euniceae, Nereideae and Ariciae, there arise 

 from tlie posterior border of the cerebral ganglion two roots which may be 

 regarded as JServ/i pharyugei superiores, and wliicli unite near their origin 

 into a Ga?iglion pharyjigeum saperius. From this last pass off posteriorly 

 delicate threads which form many ganglia upon the oesophagus, and after- 

 wards spread over probably many other parts of the digestive canal. 



Beside this Plexus splanchnicus superior, there is sometimes a Plexus 

 splanchnicus inferior — formed by other roots which pass off inferiorly 

 from the brain; part of these form under the oesophagus a Ganglion pha- 

 ryngeum inferius, while others, passing backwards, constitute Nervi pJuL' 

 ryngei and ossophagei.'^^^'^ 



The Aniphinomae have on each side of the abdomen a very remarkable 

 ganglionic chain. Their ganglia intercommunicate, not only by longitudinal, 

 but also by transverse anastomoses, with the central mass of the nervous 

 system. Among these last, those which are given off from the anterior 

 lateral ganglia, join the connecting filaments of the oesophageal ring ; while 

 the others, arising from the posterior lateral ganglia, go to the various 

 ganglionic enlargements of the ventral cord.^^*^^ 



It has not yet been possible to ascertain the signification of these lateral 

 ganglionic chains. 



CHAPTER IV. 



0RGAN3 OP SENSE. 



I. Organs of Touch. 



§ 149. 



With the Annelides, the sense. of touch is particularly developed at the 

 cephalic extremity.^^' With some Lumbricini, this extremity is prolonged 

 into a kind of tentacular proboscis. ^'^ The Branchiati have special and 



15 Cuvier (Le^. d'Anat. Comp. II. 337) has no- 17 These two ganglionic chains were first de- 

 ticed with Aphrodite two nerves passing back- scribed by Stanniu.t with Amphinome rostrata 

 wards which ought to be regarded as of a splanch- (Isis, 1831, p. 9S0, Taf. VI. fig. 4). He saw three 

 nic nature; but Grube (Zur. Anat. d. Kiemen- ganglia connect with the oesophageal ring on each 

 wiirmer, p. 58) has been unable to find them even side. But Grube (De Pleione carunculata, p. 10, 

 in the same species. fig. 5) has seen six on each side with Amphinome 



16 S^annjus (Isis, 1831, p. 986, Taf. VI. fig. 8, r. carunculata. These lateral ganglia, moreover, 

 r.), and Grube (De Pleione carunculata, 1837, p. 9, i-emind one of those described by Warner, as al- 

 fig. 5, r.), have seen with certain speeles of Amphi- ready noticed with PontobdeUa muricata. 

 nome the two roots of the Plexus splanchnicus 1 According to Rathki (Danzig. Schrift. loc. cit. 

 superior, but were unable to trace them further, p. 91, 100), the two cephalic and respiratory fossae 

 However, with Eunice Harassii, Grube (Zur. with the Nemertini, are the seat of a most delicate 

 Anat. d. Kiemenwiirmer, p. 43, Taf II. flg. 9, i.) has sense of touch ; and their white, long and protrac- 

 found beside these two roots, the C;aHS-/!on 7)Aari^n- tile jiroboscis is also a tactile organ. But other 

 geum superius which they form, and the nervous naturalists attribute wholly different functions to 

 filaments which pass (ilf from this last. Quite lately, tliL'se organs. 



Quatrefages has given very xact and detailed - The proboscis is non-articulated with Ifats pro- 

 descriptions and figures of the exjiansions of the boscidea, a.ivl Euaxes Jiliforinis (Grube, IVieg- 

 Plexus splanchnicus superior and inferior, with mann's Arch. 1844, I. p. 204, Taf. VII. fig. 1). 

 Eunice Nereis, Glycera, Phyllodoce, and Arid- But it is articulated with Rhynchelmis (,Hoff- 

 nella ; see Ann. d. Sc. Nat. 1844, II. p. 81, PI. I. II. meistcr, Ibid. 1843, 1, p. 192, Taf. IX. fig. 8). 



