378 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 2 



SPECIFIC DIAGNOSIS OF MYZOTUS VITELLOSUS 



Body rather thick, elongated, rounded at each end, almost equally- 

 wide, 3.172 to 5.130 in length, 0.958 to 1.755 in greatest width. Cutic- 

 ula smooth, very thick, and often thrown into folds, striated perpendicu- 

 larly. Oral sucker subcircular, slightly wider than long, near anterior 

 end, 0.277 to 0.435 in transverse diameter. Acetabulum about ^ body 

 length from anterior end, apparently circular, 0.562 to 1.040 in diameter; 

 sucker ratio about 1 :2. Body wall on each side of acetabulum prolonged 

 to form 2 pairs of flaplike muscular lobes or flaps (fig. 59) of very irreg- 

 ular outline. Each anterior flap more or less tapering to a free, rounded 

 point. Each posterior lobe more or less separated from the anterior lobe 

 by an indentation. Size and shape of posterior lobe variable. Acetabulum 

 deeply embedded in body, typical except near its small aperture where 

 there occurs a group of circular muscles (fig. 60) more conspicuous in 

 the posterior lip. A peculiar group of longitudinal muscles (fig. 60) in 

 ventral posterior wall of acetabulum near the aperture. 



Prephar\'nx very short; pharynx of about equal length and width, 

 0.180 to 0.337 in diameter; esophagus lacking; ceca broad, extending to 

 posterior end of body, often slightly sinuous, ending blindly. 



Testes tandem, smooth, close together, intercecal, wider than long, 

 about in middle of hindbody, posterior testis often subtriangular, post- 

 testicular space variable. Cirrus and cirrus sac lacking. Seminal vesicle 

 an uncoiled tube, free in parenchyma, entirely dorsal to acetabulum, clavi- 

 form and almost straight except for its curve around acetabulum. A short 

 pars prostatica joins uterus at middle of anterior surface of acetabulum to 

 form a fairly long genital sinus. Genital pore median at anterior edge of 

 acetabulum, well buried within body folds. Prostatic cells around male 

 tube and sinus. 



Ovary smooth, ovoid, wider than long, median, not far anterior to 

 anterior testis. Mehlis' gland very large, immediately preovarian. Semi- 

 nal receptacle flask shaped, chiefly between ovary and anterior testis. 

 Laurer's canal large and muscular. (In one sectioned specimen this canal 

 was distended with sperm cells with heads directed toward the ootype in- 

 dicating that Laurer's canal functions in copulation.) Uterus between 

 ovary and acetabulum. Vitelline follicles large, filling most of body from 

 middle of oral sucker to posterior end, confluent in forebody and also 

 posterior to testes, dorsal, ventral, lateral, and median to ceca. Eggs thin 

 shelled and variable in size. In four specimens, eggs were 61 to 68 by 31 

 to 39 /x, but in one 5.130 specimen they measured 95 by 42 /a. 



