284 transactions liverpool biological society. 



Alimentary Canal : Burrowing. 



The alimentary canal consists of (1) an eversible 

 buccal mass and pharynx or " proboscis " generally of a 

 pinkish colour in young or middle aged specimens, due 

 to the contained blood-vessels, but in old specimens liable 

 to become darkly pigmented ; (2) a cylindrical, pinkish or 

 greenish brown (esophagus, often transversely wrinkled, 

 which pierces the three diaphragms, and, just behind the 

 level of the last of these, bears a pair of glands ; (3) the 

 stomach, which has yellow walls on which are numerous 

 blood streams, extends from the level of the heart to that 

 of the eleventh or twelfth setse, and gradually merges into 

 (4) the intestine, which is yellowish brown or dark olive 

 green in colour, and extends tn the posterior end opening 

 at the anus (fig. 23). 



During life the " proboscis " is being constantly 

 everted and withdrawn, carrying sand into the oesophagus. 

 During eversion the buccal mass is first extruded, this is 

 armed with several rows of curved, bluntly pointed, vas- 

 cular papillse, which in old specimens are capped with 

 chitin (figs. 1, 3 and 4). Then the more globular pharynx 

 covered with minute rounded processes is protruded. 

 These papillee, which are covered by a thin cuticle, have 

 an axis containing muscle fibres and connective and 

 nervous tissue covered by a columnar epithelium, in which 

 numerous mucus-forming cells are present. Among the 

 columnar cells there are here and there fine fusiform 

 sense-cells, the drawn-out tips of which project into or 

 through the cuticle covering the papillae. 



The oesophagus is a thin-walled, distensible tube, 

 which is lined by elongate, columnar cells, among which 

 are swollen mucus-forming cells and occasional gland cells 

 of other kinds, the latter being more numerous in the 



