362 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 2 



tentacles on the acetabulum. It agrees with Anisoporus except that the 

 ceca open into the excretory vesicle rather than to the outside. Genitoco- 

 tyle Park, 1937 is also a related genus. Genitocotyle has the accessory 

 sucker but no tentacles on the acetabulum, and apparently its ceca end 

 blindly. There is considerable doubt if either of these characters should be 

 of generic rank (for example, the acetabular processes are not considered 

 generic in Opecoelus, and the uroproct is not emphasized in the genus 

 Stephanostomum). Anisoporus, Opecoeloides, and Genitocotyle should 

 all be considered to be in the subfamily Opecoelinae. 



A. eucinostomi is very different from A. cobraeformis in shape of the 

 forebody, in location of the accessory sucker which is median rather than 

 lateral, in lacking a genital sucker, in more anterior extent of the vitel- 

 laria, and in longer esophagus. 



Anisoporus thyrinopsi, new species 

 (Plate36, fig. 34) 



Host: Thyrinops pachylepis (Giinther) 

 Location: Intestine 

 Locality: Port Utria, Colombia 

 Number: One specimen in one of 10 hosts 



SPECIFIC DIAGNOSIS OF ANISOPORUS THYRINOPSI 



Body slender, widest at acetabular level, 1.538 by 0.307; forebody 

 0.412. Oral sucker longer than wide, 0.120 in transverse diameter; ace- 

 tabulum 0.195 in diameter, with three pairs of papillae. Genital pore to 

 the left, opposite base of phaiynx. Accessory sucker to the left, midway be- 

 tween genital pore and acetabulum. Short prepharynx; pharynx 0.097 

 long by 0.048 wide; esophagus 0.135 long; intestinal bifurcation at an- 

 terior edge of acetabulum. Testes small, smooth, longer than wide, tan- 

 dem, separated by a short distance; posttesticular space about Yz body 

 length. Cirrus short ; pars prostatica long but with few cells ; seminal ves- 

 icle sinuous, extending almost halfway between acetabulum and ovary. 

 Ovary subspherical ; vitellaria from posterior edge of acetabulum to pos- 

 terior end of body ; eggs 41 to 46 by 28 to 29 i-i. 



The name thyrinopsi is for the host. Being based on a single specimen, 

 this species is named more or less tentatively. 



Comparisons. This species is most like A. eucinostomi. It differs in 

 more slender body, more tapering hindbody, shape of testes, and much 

 longer seminal vesicle. 



