174 



THE ANNELIDE3. 



§160. 



It is remarkable that the branchiae are perhaps entirely wanting, with 

 the Aphroditae,'^' while they are often highly developed, partly in a 

 pectinate and partly in a fasciculate manner, with the Euniceae, Auiphino- 

 mae, and Arenicolae/* 



with Gti/cera, Nereis, Lycaxtis, Nephti/n, and 

 ottiLTS ; but witli Cirratu/itu, they are very Idii^. 

 With Phyllodo'-.e, and Atciopa, there are flat- 

 tened lobules. li\il\v\l\\ L'unbrinereis, Aglaura, 

 and sinie other allied ireiiera, these are wlrilly 

 wanting,' ; see Milne Edwards, Classif. l.)C. cit. 

 The r|U,-stii)n here arises if the Dorsibranchiati 

 wh ch have atrophied branchiae, have not there- 

 fore internal respiratory organs. It is at least 

 probable that the two pairs of remarkable net- 

 works surr >u:i;liai; the jjharynx of Nerei<i an.l 

 whieh have };iven rise to various interpr •tations 

 (see /iathkc', Do 15 >pyro et Nerei li, p. 4S, Tab. II. 

 fig. 5, bb, fl^'. S, f, ;r, h, and Tab. 111. ti-. U ; 

 also Milne Elwctrdx, .Van. d. Sc. Nat. X. ISiS, 

 p. 210, I'l. Xll. fi;^. ],o, p) are properly iiit^M-nal 

 brano'iiae. Tli"y receive the blood from thedjrsal 

 vessel throu:j;h two lateral vessels, and it is returned 

 to the median ventral vessel by two others which 

 are alsj lateral. Moreover, according to Rathki 

 (loc. cit. p. 40J, there is, between, every two fiet 

 upon both sides of the segments of the body, a small 

 orifice opening into the cavity of the body and 

 through which water for respiration can pass. 



7 Different observers have equally different 

 opinions upon the brancluae of these animals. For 

 my own part, I have found no trace of these 

 organs, either internal or external with Aphroiite 

 aculeata, and hystrix. I suppose, therefore, that 

 water enters the cavity of the body by oritices 

 which are very small and difficult to be seen, and 

 comes in contact with tlie entire vascular system. 



Milne Edwards (Regne anira. illustr. Ann^- 

 liles, W. XVUI. fig. 2', c)ha3 figured rudiment- 

 ary branchial lobules with Aphrodite aculalea, 

 v/hich are crenulated and c incealed between the 

 scales, and are, perhaps, invisible, when the animal 

 is in a fresh state. Jloreover, Sharpey (Cyclop. 

 Anat. and Phys. I. p. 61S), having observed with 

 the same species a very active ciliary motion espe- 

 cially upon the external surface of the intestine 

 and its coeca, it is very probable that here, as with 



the Asteroldae, the respiration occurs by water 

 entering the cavity of the body and bathing the 



intestine. 



s With Onuphis, and Eunice, the branchiae 

 are jiectinate or semi-pinnate ; see Milne Ed- 

 ivard.i, Classific. loc. cit. With Diopalra, and 

 Cliloiia, each branchia consists of a single ramiticd 

 f.isciculus ; but with the Amphinomae, and Areni- 

 colae, there are several fasciculi ; see Milne Ed- 

 wards, loc. cit. and his plates annexed to Kegiie 

 anim. de Cuvier, .\nnelides ; also SCannius, Isis, 

 ISol, Taf. VI. With Eunice, the blood of the 

 median d irsal vessel passes first into the inferior 

 lateral vessels which have the form of cardiac 

 sinuses, and by the pulsations of which it passes 

 into the branchial vessels, whence it returns into 

 the other two dorsal vessels by the superior lat- 

 eral ones ; sec Milne Edwards, Ann. d. Sc. Nat. 

 X. 18;J8, p. 207, HI. XII. fig. 2. 



With Amphinnine, there is at the base of each 

 branchial fasciculus, in the cavity of the body, a 

 Plexus Itranchialis, closely resemljling the won- 

 derful net-works o( Nereis, and from which the 

 blood passes into two lateral vessels which here 

 exist ; see Catal. of the Physiol. Ser. kc. II. PI. 

 XIV. fig. 10, or Rymer Jones, Outlines, &c., p. 

 218, fig. 93. 



With Arenicola piscatorum, only the thirteen 

 middle segments of the body have branchial fas- 

 ciculi. Tliese comnmnicate with the ventral and 

 dorsal vessels by simple lateral vessels. 



As there exist here at the extremity of the body 

 between the two dorsal and ventral vessels, two 

 cardiac sinuses, it is probable that these force the 

 blood from before backward into the ventral vessel, 

 and thence by the lateral vessels into the branchiae ; 

 so that these inferior lateral vessels would be 

 called arteries, and the superior lateral vessels 

 which return the blood to the dorsal vessel, veins ; 

 see Milne Edwards, Ann. d. Sc. Nat. loc. cit. p. 

 215, PI. XIU.* 



* [ § 160, note S.] The respiratory organs of the 

 Annelides have been much studied by Quatrefa- 

 ges (Ann. d. Sc. Nat. XIV. 1850, p. 230), and the 

 following is his resume : 



"1. The resiiiration is at first general and en- 

 tirely cutaneous (Lumbrinereis, Lysidice, He- 

 sione, &c). 



" 2. It is stiil cutaneous, but is confined or concen- 

 trated upon particular rings of the body (Chae- 

 topteriin). 



" 3. It is localized upon certain points of each 

 ring, without the st'-ucture of these points being 

 icnsibly modified {Nereis). 



"4. The first degree of the sjiecialization of the 

 respii-atnry organ ap[)ears under the form of a sim- 

 I le cul-de-sac, or an ampulla into which the blood 

 flows (Glycera). 



" 5. The branchiae become gradually character- 



ized by the formation of a canal which communicates 

 with the more or less spacious lacunae. 



" 6. These true branchiae may be distributed all 

 along the body (Eunice sans'uinea). 



" 7. They may be concentrated upon a certain 

 number of rings situated near the middle of the body 

 (Eunice Bellii, Arenicola, Hermella, Polydora). 



" 8. They may be concentrated towards the ante- 

 rior extremity of the animal, and occupy only a few 

 rings (Terebella, Pcctenaria). 



" 9. Finally, they may be located wholly at the 

 extremity of the body, and form only a double tuft 

 {Sahella, Serpula). 



" 10. In considering sometimes the entire body, 

 sometimes each ring separately, a real distinction 

 between the venous and the arterial system may 

 nearly always be made out."- Ed. 



