518 Illinois State Laboratory of Natural History. 



organ, which is doubled on itself forward and opens by a duct 

 on the external papilla. 



Alimentary Canal. — Except for the jaws the alimentary 

 canal is most like that of Hcemopis. It is straight and simple, 

 with one pair of large posterior caeca and numerous small 

 pockets, usually two pairs per somite along the middle region. 

 The jaws, however, are of a very different form, resembling 

 those of Diplobdella. They are very high and prominent, the 

 height being greater than the length. The denticles are 

 small, sharp, and in part at least ranged in paired series 

 (PI. XLIV., Fig. 20). It is quite possible to draw them 

 apart with needles and to display the groove which divides 

 the two rows. 



Color. — The colors are described from alcoholic specimens 

 which are evidently somewhat faded and otherwise altered. 

 Light brownish drab above, yellowish below. A distinct con- 

 tinuous narrow yellow line marks the dorsimesion, becoming 

 very faint anteriorly while posteriorly it is more or less broken 

 by intrusion of the ground color. A pair of rather broader but 

 less distinct yellow lines mark the margins. Between the dorso- 

 marginal and dorso-lateral sensillre on each side is a row 

 of small irregular deep brown spots, generally well separated 

 but at intervals becoming aggregated and more or less con- 

 fluent. A very few faint and suffused brown spots are scat- 

 tered over the dorsal surface. Ventrally the only markings 

 are some rather larger reddish brown spots which are chiefly 

 aggregated along the margins and become in places confluent. 



Habits. — That this leech feeds in part at least on weaker 

 creatures is shown by the presence of remains of earthworms 

 (Allolobophora) in the canal. One of Yerrill's specimens of 

 P . jioridana was captured in the act of swallowing a small 

 lumbricoid worm. The structure of the alimentary canal 

 would also indicate a diet of this character varied by an 

 occasional meal of blood. 



