The Hirudinea of Illinois. 485 



deferentia are ventrad and laterad of the testes. A slightly 

 enlarged coiled region of the ducts in somite XI corresponds 

 to the epididymes and ducti ejaculatorii, which latter become 

 constricted before opening into the somewhat enlarged prostate 

 cornua. The latter are quite distinct from one another 

 except where they join beneath the nerve cord at the small 

 bursa. There is no true muscular atrium. 



Alimentary Canal. — The protrusible pharynx is very slender 

 and when at rest reaches into somite X, where at its base it 

 receives the pair of common ducts of the pharyngeal glands. 

 There are two of these much lobulated glands on each side. 

 The larger one extends by the side of the pharynx from a 

 point opposite to the female pore in XII to the middle of IX. 

 The main duct arises in this lobe at the junction of its 

 anterior and middle thirds. The second gland is smaller. 

 Beginning in a short duct which joins the middle of the 

 principal one, it extends forward, dipping beneath the 

 pharynx, as far as the anterior end of the main gland, where 

 it emerges from beneath the pharynx and continues forward 

 a short distance. Very frequently, but apparently not invari- 

 ably, a median annectant lobe joins the lateral halves across 

 the ventral face of the pharynx. 



The lateral creca are exceedingly well developed and their 

 numerous lateral divisions reach almost to the margins of the 

 body. Six pairs correspond very nearly to as many somites 

 (XIII to XVIII). Except the first, they are arranged as a series 

 of overlapping chevrons with the angles directed posteriorly. 

 A seventh much larger pair of creca arises in XIX and con- 

 tinues backward parallel with the intestine to about XXIII. 

 The intestine bears' four pairs of long simple c»ca which are 

 directed laterad dorsal to the last described. 



Color. — Placobdella parasitica is very richly colored. On 

 the dorsal surface the ground color of brown, greenish brown, 

 or olive green is variously spotted, striped, and blotched with 

 bright yellow, which replaces the ground color more or less 

 extensively. Two specimens entirely alike can scarcely be 

 found, so that a description applicable to all' cannot easily 

 be framed in a few words. The following, however, probably 



