The adult organisation of Paragordius varius. 389 
to lay bare the nerve cord and intestine in their whole length, which 
succeeds after a little practice; this is very necessary in these worms 
which are too long to section in their whole lengths. 
The present account deals with the anatomy of both sexes as 
found in the free state and towards the close of the parasitic period, 
i. e. when the muscular elements are fully differentiated and when the 
cuticle has its final thickness and color. One specimen of a male and 
one of a female in the “white” parasitic stage were examined also; 
but a description of these will follow later with an account of the 
whole embryology in so far as the necessary stages can be secured. 
I. External characteristics. 
The external appearance of this species has been described in 
detail elsewhere (MONTGOMERY, 1898; CAMERANO, 1897b), so that only 
a brief mention is necessary here. 
In the female the body is cylindrical before the expulsion of the 
ova; the anterior and posterior portions are narrower than the middle. 
The head end (Pl. 37, Figs. 2, 4) is obliquely truncated, so that the 
ventral margin projects further forward than the dorsal; this terminal 
portion of the head is white, and just behind it is a black cervical 
ring; the color of the trunk varies from a light brown or yellowish 
to a dark brown. The posterior end of the body is trilobed, showing 
one dorsal, and two ventro-lateral lobes (Pl. 42, Fig. 78); the cavity be- 
tween these lobes is the posterior end of the cloaca, so that the inner 
surfaces of the tail lobes may be called their cloacal surfaces. The 
dorsal lobe is more triangular on cross section (Pl. 41, Figs. 71, 75), 
the lateral more crescentic. Lenght up to about 290 mm. 
In the male the head end (Pl. 37, Figs. 1, 3) is like that of the _ 
female, but the males are shorter and more slender than the females, 
and their color is generally darker. Further, the posterior end is 
bifurcated, with a pair of comparatively long, cylindrical lobes (Pl. 42, 
Figs. 81, 82); on the ventral surface of the body just in front of the 
junction of these lobes lies the cloacal aperture (Cl. Ap). 
The oblique truncation of the head end and the black cervical 
ring behind it distinguish this species from the other local ones; as 
does the trilobation of the posterior end of the female, and the 
comparatively great length and slenderness of the tail lobes of 
the male. 
