624 



Brain one half longer than greatest width; anterior margin slightly 

 concave, posterior margin quite convex. Peptonephridia large, very 

 much branched, opening into digestive tract in posterior part of III. 

 Dorsal vessel arises in XIX. Nephridia with anteseptal part equal- 

 ing postseptal part in size ; efferent duct arises from posterior end 

 of latter. Spermiducal funnel twice as long as its diameter. Sper- 

 mathecae each with duct, ampulla, and diverticula; duct about three 

 times as long as ampulla, with a few very small unicellular glands at 

 ectal opening; ampulla with about nine similar, globular diverticula. 



For discussion of penial bulb and chylus cells see pages 625, 626. 



Described from twelve sexually mature specimens. Type in the 

 collection of the Illinois State Laboratory of Natural History. Para- 

 types in the collections of each of the authors. 



The specimens on which the description of this species is based 

 were collected at Havana, Illinois, in April and May of 1895. They 

 were found abundant in the wooded banks and bottom-lands of the 

 Illinois River, under logs and in the damp rich soil, mingled with 

 decaying vegetation. 



EXTERNAI, CHARACTERS 



The body of the worm is smooth, rather robust, cylindrical, taper- 

 ing very gradually towards the two extremities. The length of 

 mature specimens is 25-30 mm. The diameter is greatest in the 

 region of the clitellum, where, in alcoholic specimens, it is 0.63- 

 0.82 mm. The number of somites varies from 57 to 66. The inter- 

 segmental grooves, except the first four or five, are indistinct. The 

 intersegmental groove IV/V differs from the adjacent ones in being 

 broader and more shallow. The prostomium is blunt, rounded, and 

 smooth. The color of the living worm is whitish. The clitellum, 

 which is on XII-XIII, is moderately developed and composed of 

 cells of but one kind. The setae vary from 2 to 4 per bundle, the 

 more usual number being 2. Each seta is rather strong, acute at the 

 distal extremity, and distinctly bent at the proximal end. 



INTERNAL CHARACTERS 



Lymphocytes. — The lymphocytes are abundant in most parts of 

 the body. They are broadly elliptical in outline, and the long axis 

 of each averages about 0.025 ^'^^i'^^- 



Brain. — The brain (PI. C, Fig. 22) is in I and II. The anterior 

 margin is slightly concave, the posterior margin is quite convex, and 

 the lateral margins are almost parallel. In transverse section it is 

 ovoid. A pair of supporting strands extending from the latero- 



