52 



PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 88 



ally to the tip, which is sharp pointed. In most cases the oral sucker 

 is ventrally placed; when the neck is extended it tends to become 

 terminal. 



The genital pore is on the median line at the anterior margin of 

 the ventral sucker. The cirrus pouch passes on, or above, the right 

 margin of the ventral sucker, and encloses the seminal vesicle; when 

 not disturbed by compression it lies dorsal to the ventral sucker. It 

 may be concealed, or more or less displaced by ova massed behind 

 the ventral sucker. The testes lie on the median line, one following 

 the other closely. There is considerable variation in their shape, 

 some being nearly circular in outline, some longer than broad, some 

 broader than long and some subtriangular. The anterior border of 

 the first testis is usually not far from the middle of the length, and 

 the distance of the second testis from the posterior end is greater 

 than the length of a testis. The ovary is near the right anterior bor- 

 der of the first testis, usually nearly circular in outline, but in some 

 cases broader than long. A seminal receptacle was not seen, the 

 appearance being that of sperm in the early folds of the uterus. 

 The uterus lies between the ovary and the ventral sucker, the metra- 

 term passing along the left border of the ventral sucker to the genital 

 pore. The vitellaria are diffuse, filling the posttesticular space and 

 extending to about the level of the middle of the ventral sucker. 

 They fill the marginal regions, and in many instances follicles lie 

 both dorsal and ventral to the testes and ovary. 



Host. — Summer flounder {Paralichthys dentafus) . 



Record of coUections. — Three, collected July 27, 1904, not in good 

 condition, macerated. One, collected August 9, 1904, Three, col- 

 lected August 15, 1906. One, collected August 16, 1906. Ten, col- 

 lected August 20, 1906; small, partly macerated, no spines around 

 mouth, indistinct on body. One, collected August 16, 1929, macer- 

 ated, spines evanescent; length, 1.85 mm.; breadth 0.6 mm.; ova 0.06 

 by 0.042 mm. 



Table 14. — Measurements of four specimens of Stephanostomum dentatum 



in "balsam 



Measurement 



Mm. 



Length _ 



Maximum breadth 



Oral sucker, length 



Oral sucker, breadth 



Pharjnu, length 



Pharynx, breadth 



Ventral sucker, length... 

 Ventral sucker, breadth. 

 Ova 



1.40 

 .77 

 .17 

 .18 



.18 



.24 



. 057 by . 03 



Mm. 

 2.10 

 .70 

 .15 

 .14 

 .10 

 .10 

 .17 

 .18 

 . 045 by . 03 



Mm. 

 2.80 

 1.00 

 .26 

 .18 

 .12 

 .11 

 .25 

 .21 

 .06 by. 04 



Mm. 



2.91 

 .77 

 .14 

 .19 

 .16 

 .11 

 .22 

 .23 

 . 057 by . 03 



