PARASITIC FLATWORMS 



397 



104 (97) Testes small, in center of body, separated from ovary by dense 

 uterine coils with masses of eggs; no eggs posterior to 

 testes Auridistomum Stafford 1905. 



Elongate, slightly constricted at center, with lateral auricle on each side of 

 oral sucker. Skin covered with fine scales. Acetabulum smaller than oral 

 sucker, located in center of anterior half of body. Pharynx present; crura 

 extend to posterior end. Excretory vesicle very long, extending nearly to 

 acetabulum, dividing into short lateral branches directed anteriad. Testes ob- 

 lique, near center of body; cirrus sac large, extending from posterior margin 

 of acetabulum to genital pore located between suckers and posterior to fork of 

 intestine. Ovary postacetabular, dextral. Laurer's canal in fork of excretory 

 duct; wall thick. Vitellaria continuous from right to left both above and be- 

 low crura and excretory duct, extending anteriad to posterior margin of acetabu- 

 lum. Eggs 31 by 17 /x. 



Only species known. . Auridistomum chelydrae Stafford 1900. 

 Intestine of Chelydra serpentina. 



Fig. 6S7. Auridistomum chelydrae. Vitellaria changed to correspond with later accour.'j 

 of author. Ventral view. Magnified. (After Stafford.) 



105 (68) Testes numerous, in two longitudinal series. 



Pleorchis RaUliet 1896. 



Inframedium sized distomes with oval, somewhat flattened body. Skin 

 spinous. Suckers small, equal, separated by only one-fourth body length. 

 Oral sucker subterminal. Prepharynx prominent, pharynx small, esophagus 

 extended, crura with single branch directed anteriad. Excretory system 

 imknown. 



Genital pore preacetabular. Cirrus sac absent (?). Testes numerous 

 in two rows near median plane in posterior half of body. Vitellaria in two 

 broad lateral bands from acetabulum to posterior end. Other organs con- 

 fined to small area between anterior testes and fork of intestine mostly, be- 

 hind acetabulum. Uterus short; ova scanty, 48 m long. 



Reported by Leidy from lungs of musk turtle (Aromochelys odorata 

 Latr.) as Monostoma molle. Shown by Stiles and Hassall to be distome, 

 somewhat like Distoma polyorchis Stossich. Position and relationship de- 

 pendent finally on more perfect knowledge of structure which awaits dis- 

 covery of new material. 



Fig. 688. Pleorchis mollis. Magnified. (After Stiles.) 



loO (.67) Acetabulum represented by two small suckers set close together in 

 depression on mid-ventral surface near center of body; 

 genital cloaca opens between the two suckers. 



Subfamily Cryptogoniminae Osborn 1903. 



Very small, spinous distomes of uniform width throughout, with bluntly rounded ends. 

 Oral sucker very large and prominent. Ventral sucker double, minute, withdrawn into pocket; 

 genital pore between the two. Prepharynx, pharynx, and short esophagus present; crura 

 extend to anterior margin of testes. Excretory vesicle Y-shaped, fork at oviduct, anterior 



