120 Illinois State Laboratory of Natural History. 



length of seven inches, a width of three fourths and a depth 

 of three eighths of an inch. In form, it is heaviest pos- 

 teriorly, being widest at about the eighth annulus in front 

 of the acetabulum, but tapering very gradually or scarcely at 

 all thence forward to the anterior 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 raottlings 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; and a ventral submarginal stripe of the same color 

 as the median dorsal one likewise quite frequent. The surface 

 is everywhere 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 

 (counting the one bearing the first pair of eyes as the first), 

 and one such just before the vent — one hundred and four in 

 all. All the perfect annuli are very distinct except the first 

 two, which, while well distinguished dorsally, are almost, but 

 not quite, 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, consequently, eleven 

 such grooves meeting the margin of the mouth, its posterior 

 boundary being formed by the undivided ventral portion of the 

 fifth annulus. The eyes are ten in number, placed upon the 

 first, second, third, fifth, and eighth annuli, rei)reseiiting 

 somites one to five. The acetabulum is broad oval, wider than 

 long, and measures about 10 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 vent- 

 ral annulus, — the ninety-fourth of the full series. These pores 

 open on the ventral surface just within the dark ventral line, 

 and conse((uently at some little distance from the margin of the 

 body. The male sexual opening is on the posterior part of the 



