12 ON THE ANATOMY OF MEGASCOLIDES AUSTRALIS, 
The nephridial tubes of this part, which are quite distinct from those of the rest of 
the body, will be described later. 
4,.—Alimentary Canal.—On opening the body cavity by a median dorsal incision, 
the alimentary tract with its very thin brown coloured walls, and its lumen full of 
earth, is seen to occupy almost the whole of the body cavity in the middle and 
posterior part of the animal, save the last twelve to twenty segments, where the septa, 
as above described, are strongly developed, and there is consequently a very distinct 
space maintained between the body wall and the intestine. Anteriorly however, the 
canal is quite concealed from view by the immensely strong cup-shaped septa (Fig. 2). 
A median longitudinal section gives very much the appearance, as far as the 
alimentary tract is concerned, which is represented diagramatically in Fig. 3. The 
short buccal chamber is distinguishable by the possession of very thin walls, which 
can be protruded. This opens immediately into the pharynx, the walls of which are 
as usual very thick and muscular, with special strands passing from them to the body 
wall. The pharynx extends through four somites, that is as far back as the first 
septum which bounds anteriorly the fifth segment. 
The space between the pharynx and the body wall is occupied partly by muscle 
strands, but principally by a large mass of minute tubules resembling exactly, in appear- 
ance, the numerous small nephridia present in the other parts of the body. Examined 
with a lense in situ, these structures, which there is little doubt are salivary glands, 
are seen to be a mass of minute coiled tubules, with a very strong development of 
blood-vessels upon them. Somewhat similar structures are described by Bznnam as 
occurring in Trigaster lankestert ;* in this worm “there are three pairs of grape- 
like glands” around the pharynx and cesophagus in the somites, [V., V. and VI. In 
Megascolides, on the other hand, they are much more irregularly arranged, and are 
confined to the pharynx. ‘Transverse sections show them to have precisely the same 
structure as nephridia, and after a careful search I was enabled to trace their openings 
into the pharynx. (Plate 3, fig. 10.) The glands are composed of an immense 
number of small tubules embedded in connective tissue. Each contains an intra-cellular 
duct. The structure of these is exactly similar to that of the nephridia from which the 
salivary glands, anatomically, are indistinguishable. There is present also the great 
development of blood-vessels forming a network upon the tubules. The latter are 
massed together in great numbers, and the ducts seem at intervals to join together 
into a common duct, which pierces the muscular walls of the pharynx, and opens into 
the alimentary canal. Where the opening takes place, the columnar cells lining the 
pharynx are, just as in the case of the epidermis where the nephridia open, modified 
so as to form what, at first sight, resembles somewhat a taste bulb. (Fig. 10.) The 
cells are arranged, as it were, along what would correspond to the lines of longitude on 
the surface of a sphere, being swollen out medianly where is the nucleus and tapering 
* Bunyam. Q.J.M.S., August 1886, page 96, plate 9, fig. 35. 
