The adult organisation of Paragordius varius. 439 
CAMERANO states (1888a, 1897b): “Non & dimostrata l’esistenza 
di una vera cavita del corpo; gli interstizii fra i vari organi sono 
occupati da un tessuto connettivo con grosse maglie e da connettivo 
fibroso.” 
IX. The Supra-intestinal Organ. 
In one adult female there was found a remarkable organ lying 
on the dorsal side of the intestine, its whole length being 6.4 mm, 
and its most anterior end placed 2.56 mm behind the anterior end of 
the head (these measurements being determined on a series of sections 
through the whole organ). This structure consists of a longitudinal 
tube closely applied to the dorsal side of the intestine, and of lateral 
branches which embrace the sides of the latter (S.J.O Figs. 18—21, 
Pl. 38). 
The dorsal tube is attenuated anteriorly and without a lumen 
(Fig. 21); 73 w behind this a closed lumen begins and continues 
closed for a distance backwards of 1.18 mm; in all this region the 
tube is dorso-ventrally flattened. Behind this portion the tube shows 
a more or less circular lumen (Figs. 18, 19) which extends nearly to 
its posterior end; the posterior end is attenuated as is the anterior. 
Both ends of the longitudinal duct are thus closed, and the duct does 
not stand in open communication with the intestine, nor yet with the 
body cavity (except though the mediation of the lateral branches of 
the organ). This dorsal tube varies greatly in its diameter at dif- 
ferent portions of its course, and a large swelling may be immediately 
followed by a constriction, and its lumen likewise varies in diameter 
and at some points is broken up into a number of separate lumina. 
The substance composing the wall of this dorsal duct is almost homo- 
geneous in character, and stains faintly with eosin; it shows no 
bounding outer layer. The substance is compact except that at some 
points clear vacuoles of varying size occur in it. The lumen of the 
duct is for the greater part of its extent bounded by a line that 
stains deeply with haematoxylin; and it is the presence of this deep 
line at the anterior end of the tube which permits us to say that a 
lumen is there but a closed one (Figs. 20, 21). | 
From the dorsal duct are given off 26 branches on one side and 
22 on the other; Fig. 12, Pl. 37, is a reconstruction showing the 
relative positions of these branches, though in this reconstruction the 
differences in the diameter of the lateral branches and the presence 
of contractions and dilatations of the dorsal duct are not shown. These 
Zool, Jahrb. XVIII. Abth. f. Morph. 29 
