46 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 2 



present, the rest apparently having been torn off, each sucker ellipti- 

 cal, slightly longer than wide, 0.088 to 0.092 mm. in length by 

 0.072 to 0.076 mm. in width. Anterior suckers large with membran- 

 ous septa, elliptical, longer than wide, 0.100 mm. in length by 0.096 

 mm. in width. Pharynx 0.056 mm. in length by 0.036 mm. in width, 

 bulb-shaped, longer than wide. Esophagus relatively short, intestinal 

 limbs with lateral branches. Testes relatively large extending from 

 middle of ovarian region to posterior haptor, elliptical to slightly 

 angular, smooth, unlobed, thirty-seven in number. Vas deferens rela- 

 tively wide and tortuous. Cirrus bulb-shaped with six small double 

 hooks. Cirrus 0.048 mm. in diameter. Cirrus hooks 0.012 mm. in 

 length. Genital pore well forward in mid-line at level of anterior 

 border of vitellaria. Ovary approximately in middle of body in mid- 

 line, in shape of inverted U tilted obliquely to left with open end of 

 U pointing posteriorly, lower arm broader than upper arm, length 

 of ovarian region 0.220 mm. in length by 0.203 mm. in width. Ovi- 

 duct arises from lower end of right arm of ovary. Vitelline ducts 

 arise from vitellaria at about level of middle of ovary. Common 

 vitelline duct relatively broad, passing obliquely posterior to right 

 of ovary. Vitelline glands coarsely acinous, from genital pore to hap- 

 tor, separated in front, slightly confluent at posterior end. Uterus 

 relatively wide, almost straight. No mature egg present. 



Discussion. Since there was only one specimen this species is 

 provisional. Heterobothrium normally has eight suckers. H. gala- 

 pagensis has only four. It is quite obvious that there is a vacant 

 space on the right side of the haptor where, no doubt, was once a 

 sucker. If this missing sucker were present there would still be only 

 five. Since the other generic characters are typical of the genus it 

 is provisionally placed in Heterobothrium. 



Comparisons. H. galapagensis differs from H. tetrodonis (Goto) 

 and H. ecuadori in the shape of the body which is more or less dis- 

 tinctly divided into three regions, an anterior portion in front of the 

 genital pore separated by a slight constriction, the middle part of 

 the body which tapers toward the haptor, and the posterior haptor 

 which is broad and distinctly marked off from the body. The cirrus 

 of this species has only six hooks, H. tetrodonis has ten, and H. 

 ecuadori has twelve to fourteen. 



H. galapagensis gets its name from its geographic location, the 

 Galapagos Islands. 



