$ 214. THE CEPHALOPHORA. 243 
fices are usually situated opposite each other; but in some they are so 
approximated that the stomach has the form of a caecum.” 
The intestine, having made more or less numerous ® convolutions, seldom 
forms a rectum, but opens, usually, close by the respiratory orifice on 
the right side of the anterior end of the body, and rarely at the posterior 
extremity. With the Pectinibranchia, the rectum often projects widely 
into the cavity of the mantle, as a longer or shorter prolongation upon 
whose extremity the anus is situated. 
Sagitta and the Apneusta present wide differences’ from this just- 
described type of structure. With the first, the mouth opens into a short 
cesophagus which passes directly, without any stomachal dilatation, into 
the intestine ; this last runs straight backwards, and, curving downwards, 
terminates in the anus situated on the median line of the ventral surface 
at the posterior end of the body. With the Apneusta, on the other 
hand, there is a stomach with several and often highly-ramified caecal 
appendages —which, in some species, extend even into the dorsal append- 
ages. A short rectum follows directly upon the stomach, and ends in 
an anus, often difficult to be found, and situated at the anterior part of the 
right side of the body.“ 
cartilaginous lamellae, and the third has, beside, 
numerous horny hooks which point forwards 
<Cuvier, loc. cit. Pl. IIL.). if 
7 Murex, Voluta, Sigaretus, Phyllidia, Di- 
phyllidia, and many species of Doris and Cari- 
naria. 
8 The intestine is very short and slightly tortu- 
ous with Clio, Carinaria, Thetis, Tritonia, 
Diphyllidia, Pleurobranchaea, Buccinum, Mu- 
rex, and Janthina. With the other Cephalo- 
phora, it has usually many convolutions, which are 
quite numerous especially with Haliotis, Patella, 
and Chiton (Cuvier, loc. cit. Pl. I.-III., and Poli, 
doc. cit. Tab. III. fig. 6). 
9 With the Pectinibranchia, and most of the 
Pulmonata, whose anus is near the respiratory 
orifice, the position of the first is determined by 
that of the last, and therefore is most usually upon 
the right, and rarely upon the left side. This is 
aie case also with nearly all the other Gastero- 
poda. 
With Patella, it is situated directly back of the 
head; with T'ritonia, Scyllaea, and Thetis, a 
little further back; and even still more behind 
with Diphyllidia, Dolabelia, Notarchus, and 
Pleurobranchaea. In this last genus it is above 
the branchia, while in Pleurobranchus, and Aply- 
-sia, it is behind this organ. With Chiton, Phylli- 
dia, Doridium, Bullaea, Testacella, and Onchi- 
dium, it is at the very posterior end of the body. 
With Doris, and Polycera, it is somewhat elevated 
on the side of the back and surrounded by bran- 
chiae, 
With Haliotis, it is anterior and on the left side ; 
and with Sigaretus, Fissuredla,and Emarginula, 
it is even in front of the oral cavity. 
Its position is varied with the Heteropoda and 
Pteropoda. With Carinaria, and Pterotrachea, 
itis situated at the base of the intestinal sac, — 
with Atlanta, upon a prolongation of the right side 
of the neck; with Phyllirrhoé, upon the middle of 
the right side; with Pneumodermon, directly 
behind the right pinion ; with Tiedemannia, at 
the middle of the abdomen; with Hyalaea, at the 
same point but a little at the left ; and with Cym- 
bulia and Limacina, in the respiratory cavity. 
See, for these various positions, the works espec- 
ally of Cuvier, Meckel, and Van Beneden. 
10 Krohn, loc. cit. Dp. 8. 
ll For the intestinal canal of the Apneusta, gee 
Milne Edwards, Ann. a. Sc. Nat. XVIII. 1842, p. 
330, PL X. fig. 2 (Calliopaea), also Quatrefages, 
Alder, Hancock and Embleton, Allman, and 
Nordmann, loc. cit. According toa communication 
from K éiliker, that of Rhodope is the most simple ; 
it consists only of a caecum which extends even to 
the posterior extremity of the body, and near the 
cardia sends off a short caecum which passes along 
the left side of the cesophagus to the pharynx, and 
upon the right side of the other end of the body 
terminates in a short rectum. With Actaeon, ac- 
cording to Souleyet (Compt. rend. XX. 1845, p. 94), 
the intestine, after forming a stomachal dilatation, 
bends, first forwards, then backwards, opening on 
the right side of the neck. But the descriptions and 
figures of this animal by Quatrefages (Ann. d. Sc. 
Nat. I. p. 141, Pl. IV. fig. 2, V. fig. 4) and Al/man 
(loc. cit. p. 148, Pl. VI.), are remarkably contradict- 
ory to these statements of Souleyet. According to 
these authors, the stomach is followed by a short 
rectum opening upon the right side of the neck, 
which is attended by two superior and two in- 
ferior intestinal tubes which send numerous ram- 
ified appendages into the parenchyma ,of the body. 
With Chalidis, the cesophagus is followed by four 
caeca, the two shortest of which extend in front, 
and the others behind. With Pe/ta, there is a 
large intestinal tube having many short coccal ap- 
pendages, situated in the middle of the body. With 
Aeolis, Fiabellina, Tergipes, which have only a 
single intestinal tube closed posteriorly, and with 
Zephyrina, Amphorina, and Calli , Which 
have two such, the caeca from this canal extend 
even into the dorsal appendages. With Eolidina, 
which has three i inal tubes inter 
ing by numerous transversal anastomoses, these 
last give rise to the caeca of the dorsal append- 
ages. Quatrefages (Ann. d. Sc. Nat. XIX. p. 285, 
Pl. XI. fig. 2, c.), who at first declared that the 
median tube of these animals opened by an anus 
at the posterior end of the body, has since (Compt. 
rend. XIX. p. 811) rectified this error; for here, 
as also with Actaeon, Aeolis, Tergipes, and Rho- 
dope, the anus is anterior and on the right side. 
A similar correction will perhaps be made with 
Venilia, whose stomach, according to Alder and 
Hancock (Ann. of Nat. Hist. XIII. p. 163, Pl. IL. 
fig. 7), not only sends many ramified caeca into 
the lateral appendages of the body, but-also is fol- 
lowed by a rectum, opening, they say, at the pos- 
terior portion of the back. 
nicat 
