44 ILLINOIS BIOLOGICAL MONOGRAPHS [262 



emergence enlarges to form the large receptaculum seminalis uterinum. 

 It fills the intercecal space with more or less regular loops which in general 

 go out from the middle of the body. These loops fold around the inner 

 surface of the crura and usually do not pass beyond the outer wall of the 

 latter organ. The vitellaria for the most lie outside the crura and extend 

 from the pharynx to the excretory bladder. Laterally they reach to the 

 middle of the crura and in exceptional instances to the inner wall of that 

 organ. 



Habitat: Stomach Host: Stereolepis sp? 



Locality: ? Date: ? 



Collector: ? Cat. No. 1035 Comparative 



Anatomy series. 



Habitat: ? Host: Symphaemia semipalmata 



Locality: Lincoln, Nebraska Date: ? 



Collector: ? Cat. No. 08 . 179 Ward collection 



Habitat: ? Host: Unknown 



Locality: Spokane, Wash. Date: ? 



Collector: W. E. Allen Cat. No. 08 . 183 Ward collection 



Cyclocoelum obscurum is most closely related to Cyclocoelum oiiopuncta- 

 tum Stossich and differs from that species in the more slender form, the 

 more heavily developed vitellaria and the relative size of the testes to the 

 ovary which in Cyclocoelum obscurum are twice as large as the ovary while 

 in Cyclocoelum ovopunctatum they are three times as large. 



CYCLOCOELUM MACRORCHIS nov. spec. 

 [Figure 9] 



This species varies in length from 7 to 15 mm and in maximum width, 

 which is found just posterior to the middle of the body, from 2 to 4 mm. 

 From this point the body tapers towards both ends, the posterior being 

 obtusely rounded while the anterior is considerably more attenuated. 

 It forms a moderately rounded point. The margins of the body lie nearly 

 parallel in the middle region of the body. The subterminal mouth is sur- 

 rounded by a weakly developed musculature, the oral sucker, which is 

 only a little larger than the well developed pharynx just posterior to it, 

 and measures 255 /i in diameter. The pharynx is oval in shape being about 

 one-fifth longer than wide and measures on the average 271/i long and 

 238ju wide. The esophagus in this species is on the whole well extended 

 and ranges from 331ju in the state of least extension to 662 n in that of 

 greatest extension exhibited in preserved material. At its posterior end 

 the esophagus turns ventrad and bifurcates forming the voluminous 

 crura present in this species (Fig. 9). These as in other species of this 

 genus lie parallel to the margins of the body and anastomose at the poster- 



