$$ 152, 153. 
THE ANNELIDES. 
163 
CHAPTER V. 
DIGESTIVE APPARATUS. 
§ 152. 
The digestive canal of the Annelides, which is organized after very dif- 
ferent types, opens always at the anterior part of the body by a mouth, and 
at the posterior part by an anus. 
and is usually straight, rarely having convolutions. 
It is situated upon the axis of the body, 
Often it is divided 
into many sections, to which the names of pharynx, cesophagus, stomach, and 
Intestine,may be given. The mouth is usually surrounded with thick lips, 
and, with many Capitibranchiati, it has very erectile tentacles and cirri, 
which may be not only tactile but prehensile organs. With others of 
this group, the food is taken in by the action in the water of the ciliated 
branchial rays which surround the mouth in an infundibuliform or spiral man- 
ner.” But usually the food, both soft and solid, is seized by the protube- 
rant lips, and swallowed by the very muscular pharynx. Many Annelides can 
also suck in liquid food through their organs of deglutition.© The stomach 
and intestine is lined with ciliated epithelium. The intestinal canal, whose 
walls are in general very thin, is either closely embraced by the parenchy- 
ma of the body, or, when there is a cavity of the body, is supported and 
constricted by numerous muscular septa. 
LL Organs of Deglutition and Mastication. 
§ 153. 
The mouth of the Nemertini is situated upon the ventral surface, and 
usually at some distance from the cephalic extremity. It is a longitudinal 
orifice opening into a long, muscular and very spacious pharyngeal tube.” 
This tube is intimately united with the parenchyma of the body, and after 
passing a short distance backward, joins directly with the intestinal canal. 
With many Hirudinei, the mouth is at the anterior extremity. Its ante- 
rior border projects so as to form a kind of lip, which the animal can vol- 
antarily change into a sucker. 
1 Terebella, Amphy .rite, and Siphonostomum. 
2 Sabella, and Serpula. 
8 Many Hirudinei. 
4 This is true of the Hirudinei, and many Nemer- 
tini. 
5 With the Chaetopodes. 
1See Delle Chiaje, Memorie loc. cit. Tav. 
LXXVIII. fig. 8. b. (Polia geniculata) ; Huschke, 
Isis, 1830, Taf. VII. fig. 2 (Notospermus drepa- 
nensis) ; Grube, Aktinien, Echiaod. und Wiirmer, 
&c., loc. cit. fig. 7, a. (Meckelia annulata) ; Rath- 
Ke, Danzig. Schrift. loc. cit. Taf. VL. fig. 8. b. (Bor- 
dasia striata) ; and Ehrenberg, Symbol. Physic. 
Phytozoa Turbellaria, Tab. IV. fig. 4. g. (Micrura 
Jfasciolata). Ehrenberg, moreover, was deceived 
in regarding this mouth as the opening of the gen- 
ital organs, and in taking the proboscideal organ of 
this species, for the true mouth. There is yetin 
this respect much contradiction among naturalists. 
Other species have a complete oral sucker, 
Thus Duges, with Polystemma (Prostoma) arma- 
tum (Ann. d. Sc. Nat. XXTI. 1830, p. 74, Pl. IL. 
fig. 5), and Quatrefages, with Nemertes man- 
dilla (Icon. du Régne anim. de Cuvier, Zooph. Pl. 
XXXIV. fig. 2), regard the long canal which opens 
at the cephalic extremity, as the pharyngeal tube, 
and the spines at its base as masticatory organs ; 
while Orsted (Beschreib. d. Plattwtirmer, p. 22, 
Taf. III. fig. 41, 49, 50) regards this whole appa- 
ratus with Tetrastemma as a copulatory organ 
(see below). In my opinion, the animals here cited 
do not belong even to the Nemertini. 
2 Borlasia (Rathké, loc. cit. p. 96, Taf. VI. fig. 
10, 11) and Polia (Delle Chiaje, loc. cit. II. p. 
407, Tav. XXVIIL. fig. 3, j., or Isis, 1832, p. 648, 
Taf. X. fig. II. 8, j.). With Meckela annulata, I 
have found the pharyngeal tube arranged in the 
same way. 
