30 



Papers from the Marine Biological Laboratory at Tortiigas. 



and caudad, its basal portion containing the seminal vesicle and lying- 

 dorsal to the anterior border of the ventral sucker, or, in contracted 

 specimens, along the right border of the ventral sucker. The prostate 

 gland is represented by many cells inside the cirrus-pouch, around the 

 ejactilatory duct and folds of the seminal vesicle. The testes are 2, close 

 together, one behind the other, or very slightly diagonal, oval, or, under 

 pressure, more or less lobed. Ovary close to anterior border of anterior 

 testis, a little to the right side, lobed, especially on the posterior border, 

 where usually about 3 lobes can be distinguished. A yolk-reservoir, in 

 most cases pyriform in shape, lies dorsal and in front of the ovary, and 

 a seminal receptacle in front of the yolk-reservoir toward the left side. 

 The vitelline glands are diffuse masses along the margins from the pos- 

 terior end to the posterior folds of the uterus, and in two rows behind 

 the posterior testis, one on each side of the median line; uterus in close 

 wreath-like folds between the ovary and the ventral sucker. The ova 

 are arranged in orderly fashion, the filaments being joined in such a way 

 as to make it appear that the ova are so many beads pendent from a 

 supporting cord. The excretory vessel is not evident in the mounted 

 specimens, but was noted in life to be a conspicuous, dark-brown vessel 

 extending from the posterior end of the body to the ovary. 



The following measurements are from 6 specimens mounted in 

 balsam: 



The diameters given are transverse. 



The ova are about 0.06 by 0.03 mm. Filaments in living specimens 

 0.17 mm. in length. 



Some details of the anatomy of this species will be found in the 

 figures. An interesting feature is shown in fig. 2)?), viz., the peculiar shape 

 of the germ cells when they are mature and ready to enter the ootype. 



This species was found in the following hosts: 



Host, Epinephelus striatus: 1906, July 7, 3 fish examined; i distome. 



Dimensions, flattened: Length 3.15; breadth anterior 0.35, middle 

 0,98, posterior 0.63; diameter oral sucker 0.23, pharynx 0.18, ventral 

 sucker 0.51 ; ova 0.047 ^Y 0.023 ; length of filament 0.17. 



1906, July 8, I fish, 3 distomes; July 12, 2 fish, few distomes; July 

 13, I fish, 8 distomes. 



1907, July 2, I fish, 8 distomes; July 8, i fish, 2 distomes. 

 Host Epinephelus morio: 



1907, July 4, I fish, 4 distomes; July 8, i fish, 2 distomes. 



1908, June 28, I fish, 2 distomes; June 30, i fish, 6 distomes; July i, 

 2 fish, 3 distomes; July 3, i fish, 5 distomes. 



