44S Prof. M'lntosh on the 



in front of the intestine. In Magelona tlie buccal and 

 pharyngeal regions receive the food, the great development 

 of the muscular and glandular tunics in the latter specially 

 pointing it out as an important part of tlie canal. The 

 smoother portion behind probably acts both as an oesophageal 

 and a ventricular chamber, and thus the food would be ])artly 

 digested before passing the barrier at the ninth body- 

 segment. 



Intestinal Region Proj^er. 



The anterior border of the tenth body-segment shows in 

 transverse section the whole tube greatly enlarged, while 

 its glandular lining is in a transition-stage dorsally and 

 ventrally. In the latter regions the tissue is composed of 

 closely arranged — almost linear — granular glands. Then the 

 entire canal assumes the soft greenish glandular condition 

 characteristic of the posterior division, its sujjcrior arch being 

 surmounted by and incorporated with the investment of the 

 two great dorsal blood-vessels. Viewed from the dorsum 

 in the living animal at the anterior tRird of the region, the 

 centre is occupied by the dorsal vessels and the compressed 

 glands, each with its central oil-globules ; and occasionally 

 a peculiar ramose or radiated appearance is assumed by the 

 contents spreading from the latter as a centre. At the sides 

 are large masses of bright orange oil-globules enclosed in a 

 limiting membrane, and the presence of these usually gives 

 the canal a deep brownish-orange colour by transmitted 

 light. Moreover, if the specimen is in good condition the 

 blood-vessels of the alimentary wall are seen as little beads 

 as they bend over the margin, under pressure. In a lateral 

 view the prominent condition of the masses containing the 

 oil-globules is still more apparent. When the gland-cells 

 are extruded into sea-water they appear as circular bodies 

 tilled with minute granules, and generally presenting a pale 

 greenish hue. As a rule the glandular mucous tissue forms 

 a thinner layer of lobate masses (in section) along the dorsal 

 arch, and a thicker and more lax coating of large glands 

 laterally ; but, of course, much depends on the degree of 

 contraction and the quantity of alimentary matter. In 

 longitudinal sections of the canal the soft glandular lining 

 is thrown at somewhat regular intervals into very sym- 

 metrical dendritic masses. Circular fibres occur all the way 

 backward, though they are so thin as hardly to merit the 

 name of a special tunic, and their feebleness is shown by 

 the marked constrictions at the dissepiments, which cause 

 the canal to assume a mouiliform appearance — well seen in 



I 



