130 MISS G@ SWEET ON THE SPERMIDUCAL 
armifera, and thinner than usual in Diporocheta Copelandi. In 
all, except Cryptodrilus illawarre and Digaster armifera, they 
are smooth and slightly curved. In C. dlawarre (P1.15. fig. 24) 
they are curiously bent back or recurved near the tip; while in 
Digaster armifera (as already described by Mr. Fletcher) the tip 
is beset with five spines, and ends in a double chelate joint 
C. Histotnoey. 
I. Spermiducal Glands. 
Typically each gland is a hollow structure, the body-wall being 
composed of long glandular cells, with a columnar cell-lining and 
covered by peritoneal membrane. Though there are considerable 
differences in the microscopic structure of the spermiducal 
gland in various forms, yet there is a certain amount of constancy 
in the relations of the external and internal structure of the 
gland. Thus the variations in its histology fall chiefly into two 
main groups, corresponding (1) to the tubular forms, and (2) to 
the lobate forms. 
1. The Tubular Forms (P1. 14. fig. 16).—Here there is a central 
duct running the whole length of the gland, and directly 
continuous to the exterior. This duct is lined throughout 
by epithelium generally of ordinary columnar cells (¢.e.), with 
a nucleus at the inner end of each (fig. 17), or sometimes of 
cubical cells (fig. 16). The imner ends of the cells are usually 
more or less horny, while the nuclei are usually clearly visible 
even when the boundaries of the cells are not so (fig. 17). In 
Megascolides australis, however, as previously described by 
Professor Spencer, these lining-cells are more granular in 
appearance, staining deeply and rarely showing any nuclei. 
Outside this lining is often a small amount of connective-tissue 
with small blood-vessels. The outermost layer of the wall of 
the duct making up the bulk of the gland is composed chiefly of 
coarsely granular gland-ceils (g.c., Pl. 14. fig. 16 & Pl. 15. fig. 17). 
Each of these has a pear-shaped outer end, containing a nucleus 
often pushed to one side: it has a long narrow duct-like inner 
end which opens into the lumen of the gland, between the cells 
of the columnar lining—sometimes singly, e.g., in Megascolides 
roseus, M. australis, M. attenuatus, M. insularis, M. hobartensis, and 
Diplotrema fragilis; and sometimes in groups, especially where 
the lining is at all horny, e.g. in Megascolides intermedius (fig. 17), 
