The adult organisation of Paragordius varius. 449 
the intestine (the intestine connecting with its dorsal side at its most 
anterior end). There are two sharply distinguishable portion of the 
cloaca: 1) a much shorter anterior glandular portion (GI. Cl Figs. 78, 
79), and 2) a much longer posterior cuticular portion (Cu. Cl). It is 
the latter portion that from its structure appears to be invaginated 
hypodermis, i. e. a proctodaeum; while the glandular is so different 
histologically that it has probably a different embryonic origin. 
The anterior glandular portion (Gl. Cl Figs. 78, 79) has 
a length in an individual of 248 mm, of only 253 «, and is lined ex- 
teriorly by a sheath of small-celled parenchym. Its wall consists of 
a high, glandular epithelium (GI. Cl Fig. 48, Pl. 40), which secretes a 
thin fluid (Gl. Secr) that stains red with eosin and generally appears 
coagulated. Before oviposition these cells are slender, but during ovi- 
position they are more rounded, often nearly spherical, owing to the 
accumulation of secretion within them. Posteriorly, where this glandular 
region joins with the cuticular region of the cloaca, is found the nar- 
rowest portion of the cloacal lumen (Fig. 79, Pl. 42), and there the 
glandular epithelium is deflected to form a ring; this constriction 
would probably act as a valve. 
The posterior cuticular cloaca (Cu.Cl Figs. 78, 79) is 
sharply demarcated from the anterior. Most posteriorly, on the inner 
surface of the tail lobes, the cloacal epithelium (Cl. Epi Fig. 71, Pl. 41) 
is exactly similar to the hypodermis (Hyp) that lines the outer sur- 
face of the tail lobes, except that the cuticula (Cl. Cut) on their inner 
surfaces lacks the areolar layer. By a perfectly gradual change in 
structure the cloacal epithelium becomes different more anteriorly 
(Cl. Epi Figs. 50, 54, Pl. 40; Figs. 71—73, Pl. 41); and from behind 
forwards not only does the lumen of the cloaca decrease in diameter, 
but the epithelium becomes gradually thicker. At the anterior end 
of the cuticular cloaca, where the cuticula is naturally of a black color 
(P. Cl Fig. 78, Pl. 42), the epithelium is very high and composed of 
cylindrical cells (Cl. Hpi Fig. 50, Pl. 40) with larger nuclei (N), 
between which are smaller, clearer cells with much smaller nuclei, 
probably gland cells. The cuticula (Cl. Cut) in this region is not 
clearly demarcated from the substance of the cell bodies, but beneath 
the very thin homogeneous layer (H. Cut) of the outer cuticula is a 
non-lamellated cuticula which covers the efids and sides of the large 
epithelial cells, as shown in Fig. 50. This portion of the cuticula, 
which corresponds in position to the fibrous cuticula of other regions 
is seen to be very thick, and composed of radiating fibres (fibres 
