174 
THE ANNELIDES. 
$ 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, Amphino- 
mae, and Arenicolae.® 
with Glycera, Nereis, Lycastis, Nephtys, and 
others 5 but with Cirratulus, they are very long. 
With Phyllodoce, aid Alciopa, there are flat- 
tened lobules. But with Lumbrinerets, Aglaura, 
and some other allied genera, these are wholly 
wanting ; see Milne Edwards, Classif. loc. cit. 
The question here arises if the Dorsihranchiati 
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 surrounding the pharynx of Nereis and 
which have given rise to various interpretations 
(see Rathké, De Bopyro et Nereide, p. 48, Tab. II. 
tig. 5, bb, fig. 8, f, g, h, and Tab. IIT. fig. 14; 
also Milne Edwards, Ann. d. Sc. Nat. X. 1838, 
p. 210, Pl. XII. fig. 1,0, p) are properly internal 
branchiae. ‘They receive the blood from the dorsal 
vessel through two lateral vessels, and it is returned 
to the median ventral vessel by two others which 
are also lateral. Moreover, according to Rathké 
(loc. cit. p. 40), there is, between every two feet 
spon both sides of the segments of the body, a small 
‘orifice opening into the cavity of the body and 
ithrough which water for respiration can pass. 
7 Different observers have equally different 
opinions upon the branchiae of these animals. For 
my own part, I have found no trace of these 
organs, either internal or external with Aphrodite 
-aculeata, and hystriz. I suppose, therefore, that 
water enters the cavity of the body by orifices 
which are very small and difficult to be seen, and 
comes in contact with the entire vascular system. 
Milne Edwards (Régne anim. illustr. Anné- 
lides, Pl. XVIII. fig. 2*, c) has figured rudiment- 
ary branchial lobules with Aphrodite aculatea, 
which are crenulated and concealed between the 
scales, and are, perhaps, invisible, when the animal 
isin afresh state. Moreover, Sharpey (Cyclop. 
Anat. and Phys. I. p. 618), 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 
*[ § 160, note 8.] The respiratory organs of the 
Annelides have been much studied by Quatrefa- 
ges (Ann. d. Sc. Nat. XIV. 1850, p. 290), and the 
following is his résumé : 
‘7. The respiration is at first general and en- 
tirely cutaneous (Lumbrinereis, Lysidice, He- 
sione, &c). 
“+2. Itis stiil cutaneous, but is confined or concen- 
trated upon particular rings of the body (Chae- 
topterus). 
“3. It is localized upon certain points of each 
ring, without the structure of these points being 
sensibly modified (Vereis). 
“4. The first degree of the speaialization of the 
respiratory organ appears under the form of a sim- 
ple cul-de-sac, or an ampull2 into which the blood 
flows (Glycera). 
“5, The branchiae become gradually character- 
the Asteroidae, the respiration occurs by water 
enterihg the cavity of the body and bathing the 
intestine. 
8 With Onuphis, and Eunice, the branchiae 
are pectinate or semi-pinnate ; see Milne Ed- 
wards, Classific. loc. cit. With Diopatra, and 
Chlogia, each branchia consists of a single ramified 
Jasciculus ; but with the Amphinomae, and Areni- 
colae, there are several fasciculi; see Milne Ed- 
wards, loc. cit. and his plates annexed to Régne 
anim. de Cuvier, Annelides ; also Stannius, Isis, 
1831, Taf. VI. With Eunice, the blood of the 
median dorsal 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 tat- 
eral ones; see Milne Edwards, Ann. d. Sc. Nat. 
X. 1838, p. 207, Pl. XII. fig. 2. 
With Amphinome, there is at the base of each 
branchial fasciculus, in the cavity of the body, a 
Plexus branchialis, closely r bling the won- 
derful net-works of Nereis, and from which the 
blood passes into two lateral vessels which here 
exist ; see Catal. of the Physiol. Ser. &c. II. Pl 
XIV. fig. 10, or Rymer Jones, Outlines, &c., p. 
218, fig. 93. 
With Arenicola piscatorum, only the thirteen 
middle segmentsgof the body have branchial fas- 
ciculi. These communicate 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 5 
see Milne Edwards, Ann. d. Sc. Nat. loc. cit. p. 
216, Pl. XILL.* 
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 sanguinea). 
“7, They may be concentrated upon a certain 
number of rings situated near the middle of the body 
(Eunice Bellii, Arenicoia, Hermella, Polydora). 
“8, They may be concentrated towards the ante- 
rior extremity of the animal, and occupy only a few 
rings (T'erebella, Pectenaria). 
‘9, Finally, they may be located wholly at the 
extremity of the body, and form only a double tuft 
(Sabella, 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.”— Ep. 
