204 THE ACEPHALA. § 189. 
The intestinal canal is short, without a distinct stomach, and somewhat 
spirally convoluted.” Its extremity opens by a large anal orifice near the 
mouth. ® 
With the Ascidiae, the intestinal canal is quite distinct. The mouth is 
situated in the respiratory cavity, far removed from the so-called oral tube, 
or more properly speaking, the respiratory orifice. It is surrounded with 
thick lips, and has at its posterior extremity with many species, a semi-canal 
closely resembling, and undoubtedly of the same signification as the ventral 
furrow of Salpa. This canal is formed by two narrow folds arising below 
the circle of tentacles which surround the interior of the oral cavity ; it passes 
along the large curvature of the respiratory cavity, and rising upon its oppo- 
site side, ends, after a longer or shorter course, below the oral cavity.” The 
mouth opens into a short oesophagus, and this last ends in a long or round 
stomach, which is often quite circumscribed and plicated longitudinally 
on its inner surface. The intestine passes first towards the base of the 
body by a short arch, then by a longer one it rises towards the mouth, 
and thence passes to the anal tube, opening, by a fringed anus, sometimes 
“close behind the mouth, and sometimes further below it. 
With the Brachiopoda, the mouth is simple and concealed between the base 
of the two tentacular arms. With Terebratula, the esophagus is very long and 
curving, opening into a large stomach ; but with the other Brachiopoda, 
the stomachal dilatation is wanting, and the intestine is simply convoluted. 
With Ordicula, and Terebratula, the intestine is short, and has only a single, 
convolution which passes to the right and terminates in a lateral anus hid- 
den between the lobes of the mantle. But with Linguda, it is much longer, 
and its turns are quite numerous; the anus here is lateral also, and opens 
through a small papilla which projects from the cavity of the body into 
that of the mantle.© 
With the Lamellibranchia the intestinal canal is highly developed, but 
always buried in the midst of other abdominal viscera. The mouth, situated 
at the bottom of the cavity of the mantle, and beneath the anterior adduc- 
tor muscles, is surrounded by two pairs of tentacles in the form of tactile 
lobes; these often form a furrow leading to the mouth, and along which pass 
the particles of food drawn in by the cilia. The mouth opens, either 
2 See Home, Lect. on Comp. Anat. II. Pl. 
LXXIL (Salpa Tilesii). 
3 For the oral and anal orifices of Salpa, see the 
figures of Cuvier, and Savigny, loc. cit. Some 
species however differ from the descriptions here 
given. Thus, according to a preparation in Hun- 
ter’s Museum, the intestine of Salpa gibbosa has © 
two caecal appendages (Home, Lect. &c. Pl. LX XI. 
fig. 2,3, and Catalogue of the Phys. Series, I. p. 
132, Pl. VIL. fig. 1, 2,i.i.), The intestinal canal 
4f Salpa pinnata presents a still more remarkable 
exception. No nucleus is formed, but the mouth 
opens directly into the stomach which is curved 
aud sends off an intestine in front, and the anal 
orifice is situated near the anterior extremity of the 
ventral groove ; see Cuvier, loc. cit. p. 11, fig. 25 
Home, loc. cit. Pl. LXXIII. fig, 2, and the Catalogue 
of the Phys. Series, I. Pl. VI. fig. 4. 
4 Savigny has described this canal with the most 
different Ascidians as a Sillon dorsal; see the 
figures (loc. cit. Pl. VI. &c.) of Cynthia, Phaliu- 
82a, Diazona, Synotcum, Aplidium, Eucoelium, 
Polyclinum, Botryllus, Pyrosoma, &c. 
Carus also has called the attention to this canal 
with Cynthia microcosmus (Nov. Act. Acad. 
Physico-Med. loc. cit. p. 432, Tab XX VII. fig. 1, 2, 
¢). 
With Phallusia intestinalis, there is, opposite 
this canal and upon the side of the respiratory cav- 
ity corresponding to the anal tube, a longitudinal 
row of very long thickly-set filaments, extending 
even to the oral aperture. Eschricht has seen a 
row of similar tentacles with Chelyosoma ; see loc. 
cit. p. 10, fig. 4, 6, z. 
5 The stomach is elongated with Boltenia, Phal- 
lusia, Cynthia, Sigillina, and spherical with 
Aplidium, Eucoelium, &c. Its longitudinal folds 
are often very distinctly marked externally by deep 
grooves, as is the case with Sigillina, Aplidium, 
and Botryllus; see for this, Savigny, loc. cit. 
According to him also there is a small caecum at 
the base of the stomach with Botryllus Schlos- 
seri, and polycyclus; see Mém. &c. p. 201, Pl. 
XX. fig. 52, Pl. XXL fig. 14, c. 
6 Upon the course of the intestine with the Asci- 
diae, see Cuvier, Savigny, and Home, loc. cit, Pl. 
LXXIV. and the Catal. of the Phys. Ser. I. Pl. V. 
(Phallusia). ‘ 
7 See the figure given by Owen, loc. cit. 
8 For the intestinal canal of several Brachioe 
poda, see Cuvier, Owen, and Vogt, loc. cit. 
9 With Cardium, Isocardia, Avicula, &c., these 
two pairs of gustatory lobules are very distinctly 
seen passing towards the mouth by as many lateral 
