a ee 
The adult organisation of Paragordius varius. 499 
vacuolar, and that the cells, except in the plane where they are at- 
tached to the cuticula, are separated from each other. ‘The cuticula 
(F.Cut Fig. 10) in contact with these cells is colorless, very thin, 
and lacks the areolar layer; this corresponds to the white tip of the 
head as seen with the naked eye (Fig. 4). No nerve fibres could be 
found in or between these cells. Each such cell is evidently a light- 
guiding element, with a less refractive core and a more refractive, 
denser wall, each perhaps allowing the penetration of a single light 
ray. The thinness and clearness of the overlying cuticula would 
readily allow the penetration of light into these cells. In the deeper 
portion of this hypodermis lie much smaller, spindle-shaped cells 
(E. Hyp. C.2 Figs. 9, 11), with very small nuclei; I cannot suggest 
any function for these. They are more or less similar in structure to 
the spindle-shaped cells of the hypodermis on the latero-ventral 
regions of the head. 
The capsule. This (E. Cap Figs. 2, 3, 6, 7, 13, Pl. 37; Figs. 16, 
17, Pl. 38) is composed of very long and slender cells which together 
form a network or felting. The cytoplasm (E.Cap Fig. 5, Pl. 37) is 
dense and deeply staining, the nucleus (N) elongated and rich in 
chromatin. These are evidently modified parenchym elements, and 
like those which envelope the vasa deferentia of the male. The cap- 
sule constituted by them is cup-shaped with the opening in front, and 
thickest posteriorly. The cells of the edge of the cup are inserted 
into the hypodermis and reach there to the cuticula (Figs. 2, 3, 6); 
such endings of the capsule cells are generally branched; these 
branches (E. Cap. C Fig. 34, Pl. 39) insert themselves in the dorsal, 
lateral and ventral hypodermis of the anterior end of the head, and 
may be distinguished from the chromophilic nerve fibres occurring in 
the hypodermis by their deeper stain. Bundles of capsule cells also 
line the cephalic nerves on their dorsal and median surfaces, and 
form a lamella between the cephalic nerves. The chromophilic nerve 
fibres of the dorsal nerves (Dors. N Figs. 5, 6, Pl. 37; Fig. 16, Pl. 38) 
penetrate into the posterior wall of the capsule (EZ. Cap), there ramify 
and pass forwards, some to the anterior end of the capsule. 
The retinal cells. In the cavity of the eye, besides the thin 
coagulum representing a fluid and some free spherical, non-nucleated 
masses, lie the retinal cells (Ret. C Figs. 5, 6, 13, Pl. 37). In most 
of the individuals examined these are placed against the posterior 
concavity of the capsule, but in one male they filled the greater 
portion of the eye cavity. These are spindle-shaped small cells (Figs. 8, 
