HIRCCINEA AND OLIGOCH^TA OF THE GKEAT LAKES REGION. 157 



green ami yellow, below longitudinally striped; a2 nmre closely united to (il 

 than to a3 on all anterior somites; a3 without trace of a secondary furrow; size 



large Placobdella paralitica ( p. 1 59 ) . 



jj. Much depressed, with very inconspicuous, low and smooth papillsp; integu- 

 ments translucent and not deeply pigmented, usually striped longitudinally 

 below; the union of al and a2 not especially conspicuous; the annulus 

 (i3 with a distinct incomplete cross furrow on all complete somites; size 



medium Placobdella picta (p. 159). 



jjj. Much depressed, the back with very numerous papilte, the largest of which 

 are very prominentand rough; integuments translucent; colors a mixture of 

 browns, greens, and yellows founded on a much broken longitudinal pattern, 

 often longitudinally striped below; <(3 not subdivided and the dorsal and 

 ventral furrows not accurately meeting; size la,rgti. Placobdella rugnsa( p. 160). 

 jjjj. Moderately depressed, with more or less numerous and roughened papilke; 

 integument.s translucent; colors variable, much as in the last, but lirighter 

 and with more dark pigment on the neural annulus and a niore constant 

 median dorsal dark stripe, interrupted by 5 or 6 pale spots; differs from all 

 (jther species of this key in the several pairs of accessory eyes which follow 



the compound ones; size medium Placobdella hollensis (p. 160). 



jjjjj. Not greatly^depressed, rather slender anteriorly; cutaneous papilke usually in 

 a median and one paired series, small, acute, and pale yellow or brown; 

 color pattern chiefly longitudinal brown and green stripes, interrupted 

 by light areas; a very conspicuous and constant pale band across the 

 entire width of somite VI; differing from all similar foregoing species in 

 the circle of .small papillse on the margin of the caudal sucker; size 



small PlacoMella plmln-a ( p. 160) . 



ii'i. Complete somites of 6 unequal annuli formed by the subdivision of the 3 primary rings. 



h. Three series of prominent dorsal papillse; caudal sucker large and mobile, with a 



circle of about 60 marginal papilla? and glands Ictinolnlella annectens (p. 160) . 



II. !Mouth relatively large, o('cupying the entire cavity of the anterior sucker; the pharynx not forming 

 a protrusible proboscis; eyes partly situated on the sides of the head; somites of 5 annuli. 



I. Annulus 66 not ob\ iously enlarged and subdivided. 



m. Eyes 3 pairs; male pore at XII ?»2/a2; female pore at XII 65/66; the 

 vas deferens forming a loop reaching forward of the atrium to gang- 

 lion XI .■ Erpobdella punctata (p. 163). 



II. Annulus 66 distinctly longer than the others and subdivided into two. 



n. Eyes 3 pairs; male pore at XII 62/«2; female pore at XII/XIII; the 

 atrial cornua inconspicuous and passing abruptly into the vas 

 deferens which lacks the anterior loop . ..Dinxi microstoma (p. 163). 

 nn. Eyes 3 or 4 pairs; genital orifices as in ?»; the atrial cornua promi- 

 nent and the vasa defereutia without anterior loops. 



Dinafervida (p. 163). 



GLOSSIPHOXID.€. 

 Glossiphonia stagnalis (Linmeus). 



Abundant everywhere in shallow waters, but especially so at Erie, Pa. Examples from Sandusky, 

 Ohio, bearing young to the middle of August. {PI. x.x.xii, tig. 2.) 



(90h) Lemna Pond, South Bass Island, Ohio, July 5, 1899. 



(95a and 96a) Xorth Bass, Swamp, Put-in Bay, Ohio, July 21, 1899. The commensal ciliate 

 tliat lives attached to the nuchal gland of this species occurs in particularly luxuriant colonies on 

 these specimens. 



(Ill) Pond near Hatchery, South Bass Island, Ohio, August 18, 1898. 



(Ilia) Middle Bass, Ohio, North Swamp, July 24, 1899. 



(115) South Bass Island, Ohio, swamp near East Point, August 24, 1899. 



