46 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 
cloaca (Fig. 86). The lobes may be either parallel or divergent, and hence 
are probably movable. 
Form of the Male. The anterior end (Fig. 82) as in the female, but the 
body more slender. The tail lobes (Fig. 87) are comparatively long and 
slender, cylindrical in shape, and obtusely rounded terminally. Small conical 
spicules occur on the medio-ventral surfaces of the anterior half of the lobes, 
and short hairs on their anterior surfaces. The elongate cloacal aperture lies in 
the medio-ventral line of the body, anterior to the tail lobes. 
Cuticle. On cross section (Fig. 91, a) an outer thin hyaline layer is seen, and 
an inner, much thicker fibrous layer, Embedded in the hyaline layer are small 
lozenge-shaped bodies, which stain more deeply than any other portion of the 
cuticle, and which correspond to the areolæ seen on surface views. The exter- 
nal surface of the hyaline layer of the cuticle is marked by short conoidal 
processes of the same structure as the hyaline matrix; these are not seen on 
surface views. On surface view (Figs. 91,5-93) the cuticle appears areolated: 
the areola are small, variable in size and form, and irregularly arranged. 
Sometimes they occur in groups, sometimes in interrupted longitudinal rows ; 
their arrangement varies both in different individuals as well as on different 
portions of the same individual. The areoles are irregularly polygonal in 
outline. In one female larger brown-colored areoles were present in addition 
to the smaller, lightly colored ones; the former were mainly arranged in the 
form of longitudinal ridges, and were irregularly star-shaped in outline. 
Color. Color usually lighter in the females than in the males, varying from 
%a light brown or yellowish to a dark brown (the larger individuals usually 
darker). The tip of the head is white or a pale brownish; just behind there 
is a dark ring of color, usually rusty brown or even black, rarely pale ; this 
ring is darkest at its anterior edge, and darker on the dorsal than on the ven- 
tral side of the body. At least a trace of this ring is to be seen on all speci- 
mens when mature, though the intensity of its coloration is very variable. 
Dimensions. Length of largest male seen, 350 mm.; greatest diameter, .9 mm. 
Length of largest female, 290 mm.; greatest diameter (of a flattened individual), 
2mm. The males are more slender and average considerably shorter than 
the females, 
Especial Diagnostic Characters. The trilobation of the posterior end of the 
female, the long and cylindrical tail lobes of the male, the oblique truncation 
of the head end, and the usually very dark colored ring around the head, 
render this species very easy of identification. 
Comparisons. This species has the greatest affinity to Gordius (Para- 
gordius ?) tricuspidatus (Dufour); but it differs from it in that there are no 
spicules or spines upon the tail lobes of the female, and in that the dorsal is 
narrower than the lateral lobes; further, in varius the areoles of the cuticle 
are frequently arranged into rows or groups. 
Geographical Distribution. I have examined specimens from the following 
localities: New York, Maine, Massachusetts, New Jersey, Pennsylvania, Vir- 
ginia, Kansas, California, and Guatemala; and it has been observed by others 
