The adult organisation of Paragordius varius, 431 
cervical ring (a darkening of the deeper layers of the cuticle in this 
region, Figs. 1, 4, Pl. 37). The functional value of this eye to the 
worm in its free-swimming state is obvious, in allowing it to perceive 
the source of light. 
Literature on the eye. von Linsrow (1889) is the only 
observer to have noticed eyes; he finds in G. tolosanus “Ocelli” . . 
“Dicht hinter dem Scheitelpunkt, . . . liegen an der Rückenseite . 
2 kleine, von schwarzen Pigmentkiigelchen umgebene Linsen.” His 
figure shows these only with low magnification, and from this figure 
it cannot be determined whether they lie in the hypodermis or the 
parenchym. Warp (1892) describes in detail for Nectonema a large 
closed space in the head, the “anterior chamber”, which shows certain 
resemblances to the eye of Paragordius. 
VIII. The Body Cavities, Mesenteries, and Parenchym. 
A. In the Female. 
The following is a description based completely upon the study 
of the adult structure. The term “body cavity” is used instead of 
“coelom” or “archicoel” or “schizocoel”, as being less committal with 
regard to the origin of these spaces and their embryological values. 
The term “parenchym” is also employed in a very broad sense, to 
describe the peculiar tissue of Paragordius for which a large amount 
of a dense intercellular substance is so characteristic. It is of course 
not at all comparable to the loose network of mesenchym cells termed 
“parenchym” in the Turbellaria and other Platodes. But the term 
“connective tissue” is less strictly applicable, and in the adult or- 
ganisation it can hardly be termed a “lymphoid tissue”. Hence the 
word parenchym is used here simply as a designative term for con- 
venience in description. 
The body cavities. No body cavities are found in the anterior 
region of the body, from the anterior point of the head backwards 
as far as the most anterior ovaries. The head (Figs. 2, 3, 6, Pl. 37) 
is filled by the cephalic ganglion, the heightened sensory hypodermis, 
the huge eye, and a small amount of parenchym around the intestine 
and ganglion. There are also no body cavities in the posterior part 
of the trunk, from the plane where the oviducts join the atrium 
(Fig. 75, Pl. 41) backwards to the posterior ends of the tail lobes 
(Fig. 71), but the space from the body wall to the cloaca is filled 
