648 ^o The American Naturalist. [July, 
ing widest at about the eighth annulus in front of the acetabulum, 
but tapering very gradually, or scarcely at all, thence forward to 
the antierior fourth, and thence more rapidly to the mouth. Its 
transverse section is depressed oval, flattened beneath the margins 
of the body obtuse. 
The color is sooty drab, varying to plumbeous black, some- 
what lighter beneath, uniform in tint, and quite without spots or 
mottlings of any sort. A darker median longitudinal stripe, 
very conspicuous and well defined, is almost invariably present ; 
a paler marginal stripe, often approaching buff,little less con- 
stantly so, anda ventral submarginal stripe of the same color as 
the dorsal one, likewise quite frequent. The surface is every- 
where smooth, and I find no external trace of segmental papilla. 
There are ninety-nine complete annuli from the mouth to the 
posterior sucker, four imperfect annuli in the cephalic lobe, and 
one such just before the vent—104 in all. All the perfect annuli 
are very distinct, except the first two,which,while well distinguished 
dorsally, are almost completely fused beneath to form the posterior 
border of the mouth. In front of the first annulus is the upper 
lip, divided by a delicate median groove. There are, conse- 
quently, eleven such grooves meeting the margin of the mouth, 
its posterior boundary being formed by the undivided ventral por- 
tion of the fifth annulus. The eyes are ten in number, placed 
upon the first, second, third, fifth, and eighth annuli, representing 
somites one to five. The acetabulum is broad oval, wider than 
long, and measures about ten mm. in its greatest diameter. The 
vent is large and surrounded by irregular radiating grooves. 
The first nephridial pore is at the anterior margin of the 
tenth complete annulus—the fourteenth in all—and the last or 
seventeenth pore at the anterior margin of the ninetieth ventral 
annulus—the ninety-fourth of the full series. These pores open 
on the ventral surface just within the dark ventral line, and con- 
sequently at some little distánce from the margin of the body. 
The male sexual opening is on the posterior part of the twenty- 
eighth entire annulus, and the female opening on the thirty third. 
Within the buccal cavity is a prominent circular fold. Maxille 
three, rudimentary, distinguishable only in sections, with an ill- 
