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THE AMERICAN NATURALIST [Vol. XLII 



The mouth is very small and situated far forward near 

 the anterior rim of the sucker in somite II. As in related 

 species, the proboscis is slender and the crop is provided 

 with seven pairs of large caeca reaching nearly to the 

 margins of the body. The caeca, however, are less deeply 

 and finely divided than in P. parasitica, each of the first 

 six pairs exhibiting only two or three rather short lobes.. 

 The intestine reaches to the posterior part of somite 

 XXIV or even beyond and then bends abruptly forward 

 toward the dorsum as an extremely narrow rectum reach- 

 ing to the minute anus situated at XXIII-XXIV. The 

 forward curvature of the rectum and the anterior position 

 of the anus are unique features in the family. The 

 salivary glands are widely scattered through the an- 

 terior two thirds of the body. On either side of the 

 esophagus in somites X and XI lie a pair of compact 

 esophageal glands which join the esophagus by a short 

 duct in somite XI. 



The reproductive organs are essentially similar to those 

 of P. parasitica. The male and female external orifices 

 are situated at XI-XII and XIIa2-a3, respectively. Six 

 pairs of testes are crowded between* the bases of the gas- 

 tric caeca. The large sperm sack and the ejaculatory duct 

 of the vas deferens form a compact snarl in somite XII in 

 the immediate neighborhood of the atrium. Nothing is 

 known of the early stages of development. 



