54 



in all cases opens inlu the pharyngeal diverlicuhim, allhoiij^h llie actual connexion can only be 

 demonstrated in a certain proportion of cases (fig. 42: PI. XIII, fig. 181). The pharynx (///.) 

 is a large organ, the walls of which are usually a good deal folded, a condition probably due 

 not t)nlv to the contraction of its own longitudinal muscles but also to that of the anterior 

 longitudinal muscles of the body. The phar\nx passes into the oesophagus (oes.), which is well 

 marked off from the pharynx, and opens into the middle of the anterior side of the large 

 stomach (s/o///.), the walls of which are much folded. Near the junction of the stalk with the 

 body, the stomach opens into a portion which may be called the second stomach {stom.'-), since 

 the histology of its walls indicates that it has an important digestive function. The second 

 stomach bends round the ventral wall of the stomach, from wliich it is separated by a ])art of 

 the third body-cavity (^. r.'M). On the termination of this part of the coelom it passes int(j the 

 intestine, which is closely apposed to the posterior wall of the stomach. The junction between 

 the second stomach and the intestine may be conspicuously indicated by a fold in the wall, as 

 shewn by M'Intosh (87) in his I'l. Ill, fig. 3. This fold is well marked in some of the more 

 lateral sections of the series from which fig. 42 is taken, but it does not appear in the section 



figured. M'Intosh remarks (p. 17) that "this peculiar fold probably indicates a tendency to 



"the formation of a second or pyloric stomach, as in Phoronis, and is therefore of considerable 

 " morphological significance". 



The dilated rectum (r.) is also partly attached to the stomach, on leaving which its 

 dor.sal surface is exposed to the third l^ody-cavity. It opens to the exterior by the transversely 

 elono-ated anus, which is not shewn in the figure. The walls of the intestine and rectum are 

 thin and probably do not secrete digestive fluids. The size of the lumen of the rectum varies 

 "■reatlv in different individuals. 



In C. levinseni (figs. 33, 34) the alimentary canal as a whole shares in the elongation 

 of the l)ody as compared with C. dodecalopkus\ but the same parts may be recognized. The 

 dorsal diverticulum of the pharynx comes into less extensive contact with the central nervous 

 system. In old individuals (fig. 33) the stomach may be greatly elongated, while the intestine 

 {int.) may pass continuously into ihe rectum (r.) without shewing the dilatation which usually 

 marks the beginning of the latter. This dilatation may, however, be as well marked in C. 

 levinseni as in the other species, as is apparent fr(;ni fig. 34 and from PI. I, fig. 6. It may be 

 encjuired whether the difference between fig. 33 and fig. 34 is one of age or whether, on the 

 contrary, it is not merely a difference in the state of muscular contraction. I regard the latter 

 as the more probable explanation, particularly when the much greater antero-posterior diameter 

 of fig. 34 is taken into account. If this be the case, the elongation of the body would appear 

 to have the result of straightening out the rectum, the lobe which overlaps the stomach in 

 fisf. i4 beine in fact the result of the contracted condition of the zooid. The elont^ation of 

 fig. 33, as compared with fig. 34, has afi'ected all parts ot the alimentary canal to a greater 

 or less extent. The oesophagus {pes^ is much drawn out, antl the antero-ventral caecum of the 

 stomach seen in fig. 34 has been obliterated in fig. 33. I have observed two or three neuter 

 individuals of C. sibogac shewing the same excessive elongation that is noticeable in i\'-^. 33; 

 and it appears natural to regard these as the extended condition of the animal. It is probable 



