The adult organisation of Paragordius varius. 463 
the mesenteries and lateral cavities are to be compared with the 
mesenteries and coelomic sacks of the Annelida. This point must be 
finally decided from the standpoint of the development, in early stages 
which have not yet been described. 
On account of these differences between the Gordiacea and 
the Annelida I have adopted the indifferent term “parenchym” for 
the tissue which lines the body cavities, not wishing to employ the 
term “peritoneum” which in the strict usage denotes the lining of a 
proved coelom. It is on the whole a unique kind of tissue, in the 
adult composed of cell bodies firmly united together by a dense inter- 
cellular substance, and its cells are not free. VEJDOVSKY holds that 
it is formed late in the ontogeny, as a proliferation of the primitive 
lining of the body cavity, and considers it to be lymphoidal. 
As to excretory organs, there are in the Nematoda a single 
or a pair of unicellular nephridia placed in the so-called lateral lines, 
which open together in the mid-ventral line of the head region. In 
the Annelida there are usually metamerically arranged metanephridia, 
or sometimes these connected by a longitudinal duct (Lanice). Neither 
of these conditions are found in the Gordiacea. VEJDOvsKŸ has 
interpreted the medio-ventral body cavity (periintestinal space) as an 
excretory organ; it has, however, no opening to the exterior. In im- 
mature stages he found in the anterior portion of this space a “braune 
Driise” opening into the intestine near the mouth. Under the name 
“supra-intestinal organ” I have described a long unpaired canal lying 
upon the dorsal side of the intestine in Paragordius, and having 
lateral diverticula; this may be an excretory organ, conveying fluids 
from the periintestinal space to the intestine, but whether it is homo- 
logous with the “braune Drüse” of Gordius remains to be determined. 
Both these organs are unpaired, in close attachment with the intestine, 
and without any opening to the exterior; they cannot be at all com- 
pared to the nephridia of Nematoda or Annelida, and appear 
to be degenerate in the adult condition. Whether the oviducts and 
vasa deferentia may be modified nephridia, as VEJDOVSKY suggests, 
depends upon their mode of origin, which is unknown; there is a 
structural character to speak against this view, namely that the epi- 
thelial lining of these ducts is similar to that of the uteri and testes, 
which would necessitate the genital organs in their full extent being 
modified nephridia. 
Finally some comparisons of minor importance may be made. 
There are in the Gordiacea no appendages nor any signs of such 
