THE GIANT EARTH-WORM OF GIPPSLAND. 9 
thinner in segments 14-19 (Fig. 2), the long muscular slips running from segment to 
segment, until after the twentieth segment the septa assume the usual membraneous 
appearance, and retain this nature until the posterior end of the body is reached (Plate 
4, fig. 20), where they again become strongly muscular. In this part, comprising 
some twenty segments, they form flat plates encircling and standing at right angles to 
the alimentary canal. There are very well-developed muscular slips, passing (Fig. 20) 
radially from the walls of the alimentary canal to the posterior face of each septum. 
The first complete septum bounds anteriorly, as may be seen from the external 
indications of the segments, the fifth segment. In front of this the body is filled with 
a-dense mass of muscle fibres surrounding the pharynx, all the spaces between being 
filled with the modified nephridia forming the salivary glands. 
Throughout the body the septa are incomplete only, as usual, on the ventral 
surface, where in the mid line is an arched space through which passes the ventral 
blood-vessel and the nerve cord. (Plate 5, fig. 21, sept, 0.) Special supporting 
muscles run to the body wall from each side of the arch. 
It is curious to note that all through the body, and especially in the middle and 
hinder regions, the insertions of the septa do not correspond with the grooves separating 
the segments ; each septum is very distinctly joined to the body wall posteriorly to 
the groove which externally forms the anterior limit of the segment of which it forms 
internally the anterior boundary. (Plate 3, fig. 14.) Hach septum (Plate 5, fig. 22, 
and plate 3, fig. 14) has, as it were, a slight pouch extending forwards in the mid 
dorsal line, and into which opens the dorsal pore, the latter therefore lying slightly in 
front of the segmental chamber with which it is thus connected by a short canal: in 
transverse section, this actually appears as a canal. At the pores the epidermic layer 
of cells dips down and lines the pore as far as the level of the inner side of the 
circular muscle-fibre layer. The longitudinal fibres run up towards the body surface 
around each pore with which they may happen to be in contact, and are inserted into 
the connective tissue immediately beneath the epidermis at its lowest position in the 
pore. The septa, as usual, are composed of radially arranged muscle fibres, of which 
only a thin layer is present, save in the very strong and thick septa anteriorly ; on 
either side is a thin epithelium of distinctly nucleated flattened cells, directly con- 
tinuous with the epithelium lining the body wall internally. 
3.—Body Wall. This may structurally be divided into two parts—(1.) That 
over the whole surface except the clitellar region ; (2.) That in the clitellar region. 
In the first of these two regions the structure is, on the whole, that which is 
characteristic of most earth-worms, though in minor points it shows variations from 
that of Lumbricus. The epidermis is represented in fig. 7, the whole body wall in 
fig. 18. Most externally is the cuticle (cut.) The cells of the epidermis have the usual 
elongate columnar form, with very distinct oval nuclei; amongst them lie numerous 
goblet cells (gob.) much larger than the others, and distinguishable also by containing 
C 
