112 PROCEEDINGS OF THE NATIONAL MUSEUM vol.88 



Hosts. — Histrio pictus, rudderfisli {Seriola zonata)^ horse mackerel 

 {Thunnus secundodorsalis) , goggler {Trachurojys crumenophthaZma) ^ 

 cutlassfish {Trichiuriis leptums) ^ swordfish {Xiphias gladius). 



Record of collections. — One, immature (U.S.N.M. No. 8307), col- 

 lected September 5, 1919, from Histrio pictus. This specimen, when 

 first noted, had been cut into three pieces, one cut passing just behind 

 the genital pore, the other a short distance back of the ventral sucker. 

 The body was minutely and transversely wrinkled, and pinkish in 

 color. Aggregate length, before flattening under pressure, about 8 

 mm. ; maximum breadth, 3.5 mm. Measurements in balsam : Length, 

 13.5 mm.; breadth at oral sucker, 1.54 mm., at ventral sucker, 2.31 

 mm., maximum breadth, at 3.5 mm. from the posterior end, 3.5 mm. ; 

 oral sucker, length, 1.12 mm., breadth, 1.26 mm.; pharynx, length, 

 0.84 mm., breadth, 0.91 mm.; diameter of ventral sucker, 1.47 mm.; 

 distance between suckers, 2.5 mm. There is no prepharynx. The 

 pharynx tapers from a breadth of 0.9 mm. at its anterior end to about 

 0.6 mm. at its posterior end. Esophagus short; the voluminous 

 intestines reach to the posterior end. The genital pore is at the right 

 posterior edge of the pharynx. The genital papilla is about 0.7 mm. 

 in length and 0.5 mm. in breadth. The opening of the uterus is not 

 clearly shown, but it appears to be behind the genital papilla. The 

 testes lie near the posterior edge of the ventral sucker. The left 

 testis is subtriangular in outline. Its anterior border is practically 

 contiguous to the posterior edge of the ventral sucker, and its 

 median end on the median line. The right testis is bluntly slipper 

 shaped, its median end contiguous to the posterior median border of 

 the left testis. It is broader than long, and at its lateral end is pro- 

 longed anteriorly until it is nearly on a level with the anterior edge 

 of the left testis. The ovary is a short distance behind the testes on 

 the median line. It is much smaller than the testes, subglobular, 

 and is surrounded by a rather thick wall. It is made up of a rela- 

 tively small niunber of large, nucleated cells. The rudiment of the 

 shell gland lies at the median and posterior border of the ovary. 

 The uterus, represented by a slender but well-defined tube, lies in a 

 tangled coil on the right side of the ovary, and passes in a wide 

 curve back to within 4 mm. of the posterior end, and forward between 

 the testes, and dorsal to the ventral sucker, toward the genital pore. 

 Certain slender, irregular, threadlike structures in the vicinity of 

 the ovary were noted. They may be rudiments of the vitellaria. 



From ruddertish: One, collected September 19, 1912. Measure- 

 ments in formalin: Length, 12 mm.; breadth, 6 mm.; thickness, 5 

 mm. Neck and suckers pale, yellowish white; body darker and 

 crossed by transverse rugae (fig. 137) . 



