§ 154. THE ANNELIDES. 165 
With the Hirudinei, the intestinal canal varies very much, especially as 
to the number and volume of its appended coeca.” Its very narrow anal 
opening is upon the back directly above the pedal sucker. With Nephe- 
dis, the canal is simple and gradually enlarges from before backwards, but 
has no coeca. 
With Branchiobdella, it is deeply constricted in several places. With 
Pontobdella, it is simple with its two anterior thirds, but there is a caecum 
on each side of its remaining portion.” This last is also true of its posterior 
‘third with Haémopis, Clepsine, and Sanguisuga.© With this last genus, 
the other portions of the canal are divided by ten or eleven constrictions 
into as many parts which send off on each side short caeca; ” while that 
of Clepsine has on each side five or six coeca, all of which may be rami- 
fied. There is a kind of valve directly behind the last two caeca, and so 
the part of the intestinal canal in front of this may be regarded as a stom- 
ach and a small intestine, while the remaining portion behind it, represents 
the rectum. © 
With the Abranchiati, the intestinal canal is short, and its esophagus 
which is usually narrow passes into a muscular pharynx, which leads into 
a stomachal dilatation. Upon these parts follow the remaining portions of 
the intestine which are separated from each other by the transverse septa 
of the body and often resemble the stomach. With a few species only, the 
stomach is remarkable for its thick, muscular walls. ; 
With some of the Capitibranchiati, the digestive canal arises directly 
behind the esophagus and has bulging portions like those of the colon. 
assuming, posteriorly, sometimes a spiral form.“ With others, the csoph- 
agus is continuous directly into the intestinal canal, which, free and un- 
attached by diaphragmatic septa, makes many turns in the cavity of the 
body, and by constrictions is divided into a stomach, small intestine, and 
rectum, 
With many Dorsibranchiati, the intestine follows directly upon the 
cesophagus, and is either straight and divided by constrictions," or assumes 
a spiral form or is without constrictions and irregularly tortuous, 
With others, the portion of intestinal canal between the pharynx and in- 
forms with the buccal orifice, a cavity distinct from 
that of the abdomen, and its anus has a kind of 
sphincter. But this is certainly an erroneous view 
of the organization of these worms: the contents 
of the cavity are sufficient alone to confute it. 
2 Moquin-Tandon, loc. cit. Pi. I-IV. 
8 With Piscicola, exceptionally, the anus is up- 
on the ventral surface of the last segment of the 
body ; see Leo, in Miiller’s Arch. 1885, p. 420. 
4 Henle, Muller’s Arch. 1835, Taf. XIV. fig. 1. 
5 Wagner, Isis, 1834, p. 130, Taf. I. fig. 1, 2. 
6 Brandt and Ratzeburg, Med. Zool. IL. p. 246, 
Taf. XXIX. B. fig. 12. 
7 Ibid. Taf. XXIX. A. fig. 19, 20, 55. 
8 With Clepsine marginata, this rectum has 
coecal appendages also; see F. Muller, in Wieg- 
mann’s Arch. 1844, I. p. 371, Taf. X. fig. 14.* 
9 With Lumbricus, the stomach is very muscu- 
lar ; see Morren, loc. cit. Tab. XI.~XIV. This is 
also true of Nats proboscidea, but not with Lum- 
briculus, and Enchitraeus. 
* [§ 154, note 8.) For many special details 
illustrating as well the histology as the anatomy of 
the intestinal canal of the Hirudinei (Piscicola, 
10 Terebella, and Sabella; see Grube. 
Anat, d. Kiemenwiirmer, p. 20, 27, Taf. it 
12, and Miine Edwards, Ann. d. Sc. Nat. X. 
1838, Pl. X. XI. 
ll Sabella ; see Carus and Otto, Erlauterungs- 
taf. Hft. IV. Taf. III. fig. 4, 6, and Wagner, Icon. 
zoot. Tab. XX VII. fig. 21. 
12 Amphitrite, and Siphonostomum. With the 
first, the stomach is long, spiral, and divided into 
an ding and ad ding portion ; see Rath- 
ké, Danzig. Schrift. loc. cit. p. 64, 86, Taf. V. VI. 
18 Amphinome, Arenicola, Eunice, and Neph- 
tys ; see Stannius, Isis, 1831, Taf. VI. fig. 10; 
Milne Edwards, Ann. d. Sc. Nat. X. 1838, Pl. 
XII. XIII. ; Grube, Zur Anat. d. Kiemenwiirmer, 
Taf. I. 
14 According to Grube (Ibid. p. 34), the intes- 
tine of Cirratulus is spiral like that of Sabedla. 
15 Ammotrypane (according to Grube, see 
Rathké, Nov. Act. Acad. Nat. Cur. XX. p. 197, 
Tab. X. fig. 18). 
Zur 
. fig. 
Clepsine, Nephelis), see Leydig, loc. cit. p. 110, 
Taf. VILI. LX. fig. 24-37.— Ep. 
