The Hirudinea of Illinois. 511 



openings of which have been described, form a conspicuous 

 mass occupying the posterior half of XIII and the entire region 

 of the floor of XIV included between the vasa .deferentia. 



Alimentary Canal. — The jaws differ greatly from those of 

 Philobdella and resemble those of Hirudo ; they are more than 

 twice as long as high and each bears about sixty-five fine 

 monostichodont teeth. The remainder of the canal is very 

 like that of Diplobddla. Each somite from X to XVIII 

 inclusive is provided with two pairs of caeca which are very 

 spacious from XIII caudad. The large posterior pair, which 

 arise from the stomach in XIX, reach backward clear into 

 XXIV or XXV. 



Habits. — Macrobdella is probably strictly aquatic and is a 

 true blood-sucker. It attacks man, cattle, turtles, frogs, 

 fishes, etc., which enter its domain, and is frequently found 

 gorged with blood. However, this is not its exclusive food. 

 In the spring great numbers of frogs' eggs are devoured. In 

 the neighborhood of Philadelphia these are sucked from the 

 masses of jelly after the gelatinous envelopes have been cut 

 by the leech's teeth. Large numbers of tubificid worms 

 have also been found in the caeca. Whitman ('86) gives an 

 account of the sensory reactions of this species. 



Philobdella Yerrill. 

 Philobdella gracile sp. nov. 



Philobdella floridana Moore ('98), not Verrill ('74). 



Diagnosis. — Copulatory gland pores in two nearly counter- 

 part groups related respectively to the male and female 

 genital orifices ; male pore at XII b 2 fa 2, in mature examples 

 opening into a conspicuous deep pit, female pore at XIII b 1 ; 

 alimentary canal of Hmnopis type, the denticles about 35, 

 partly distichodont ; annulation essentially as in Hamopis 

 marmoratis; color partly non-metameric blotches. 



