IV ALIMENTARY CANAL—COELOM 123 
4 
the right and left to encircle the front of the pharynx as the 
peripharyngeal bands. These unite again dorsally to form the 
epipharyngeal (or hyperpharyngeal) groove which leads backwards, 
corresponding to the hypopharyngeal groove below (see Fig. 74, A), 
till the posterior end of the pharynx is reached. 
The remainder of the simple alimentary canal is straight, and 
is scarcely differentiated into regions. A slight narrowing of the 
tube behind the pharynx has been called the oesophagus, and a 
m.b.a, median  bran- 
chial artery; p.6, 
primary bar; sk, en- 
dostylar and branchial 
rods and __ skeletal 
plates ; 2.4, tongue- 
bar. (After Lankes- 
ter.) 
(a 
PR: Fic. 76.— Transverse sec- 
ae tion of the ventral 
[x part of the pharynx 
ee? of | Amphioxus. C, 
fq * — 
sk. ae Coelom ; e, endostyle ; 
i Bs gl, endostylar glands ; 
“3 2 
ae 
e 
slight enlargement which follows, the stomach. From this point 
the intestine tapers backwards to the anus (Fig. 71, p. 116). The 
ventral edge of the stomach gives off a blind pouch, the hepatic 
caecum or saccular liver, which runs forwards on the right-hand 
side of the pharynx (Fig. 74, A, /). This is a digestive gland, is 
lined with glandular epithelium, and apparently corresponds with 
the liver of Vertebrata. There are no other digestive glands in 
connexion with the alimentary canal of Amphioxus. 
Coelom.—lIn the young larva there are at first (as in Balano- 
glossus) five coelomic spaces, a median anterior “ head-cavity,” a 
pair of antero-lateral “ collar-cavities,” and a pair of more posterior 
long lateral grooves from which arise, in the later larva, the seg- 
mented myotomes and ventrally a large coelomic space surrounding 
the alimentary canal and separating it from the body-wall. In the 
adult animal, however, the coelom has been so much displaced by 
the formation of the spacious atrium that in front of the atriopore 
it can only be recognised as a series of canals and crevices. The 
relations of coelom to atrium in the region of the intestine are 
