14 THE HANCOCK PACIFIC EXPEDITIONS VOL. 2 



ward) and in none did they reach the extreme posterior tip of the 

 body. The vitellaria largely fill the body posterior to the testes and 

 form two longitudinal intercecal, posttesticular areas. 



GENERIC DIAGNOSIS OF APOCREADIUM 



Elongate distomes with body much flattened posterior to mid- 

 body where the edges are very thin. Acetabulum anterior to mid- 

 body, larger than oral sucker. Pharynx well developed with an an- 

 terior region of circular muscles. Ceca extending not very far apart 

 to near posterior end. Testes in midbody region, tandem, intercecal, 

 close together. Seminal vesicle large, undivided, sac-like. Cirrus and 

 cirrus sac lacking. Prostate cells poorly developed. A tubular genital 

 sinus present. Genital pore median at anterior edge of acetabulum. 

 Ovary spherical, pretesticular, slightly to the right. Mehlis' gland 

 large, postovarian; Laurer's canal and seminal receptacle present. 

 Uterus pretesticular, largely to the left. Vitellaria follicular in sides 

 of body, confluent posterior to testes. Excretory vesicle I-shaped with 

 2 pairs of anterior and 1 pair of posterior tubules. Lymphatic sys- 

 tem of 4 large longitudinal vessels branching at least in posterior 

 half of body. Type species: Apocreadium mexicanum. 



SPECIFIC DIAGNOSIS OF Apocreadium mexicanum 



(Measurements in mms.) 



Body rounded anteriorly, pointed posteriorly; scaled to mid- 

 body; 2.151 to 4.110 by 0.757 to 1.096. Acetabulum 1/4 to 1/5 from 

 anterior end, 0.352 to 0.502 in diameter, with transverse aperture; 

 oral sucker 0.225 to 0.315 in diameter. Prepharynx and esophagus 

 present; intestinal bifurcation midway between suckers. Four longi- 

 tudinal vessels branched in posterior half of body. Genital pore me- 

 dian at anterior edge of acetabulum. Seminal vesicle just posterior 

 to acetabulum, overlapping ovary; genital sinus tubular, shorter 

 than ejaculatory duct. Ovary spherical; seminal receptacle extend- 

 ing anterior to ovary; uterus to left of ovary; eggs 61 to 67 by 31 

 to 34 /x; vitellaria from near posterior edge of acetabulum to near 

 posterior edge of body. 



Host: Labrisomus xanti Gill 



The name Apocreadium is from apo: 'away from and creadium 

 and implies the fundamental differences between this trematode and 

 the AUocreadiidae. The name mexicanum is for the locality. 



