50 Papers from the Marine Biological Laboratory at Tortugas. 



opposite, a short distance back of the ventral sucker. They are rather 

 small and long oval, and are near the lateral margins of the body. The 

 ovary is an oval body dorsal to the right caudal margin of the ventral 

 sucker. At its left side is a globular, rather strong- walled sac, in the 

 mounted specimen very slightly stained and empty, which seems to be the 

 seminal receptacle. The vitelline glands are compact, subglobular bodies, 

 about 6 or 8 visible on each margin without deep focussing. They lie 

 on each margin lateral to the ventral sucker, the cluster on the right 

 occupying a little less, and the cluster on the left a little more, than the 

 diameter of the ventral sucker. The uterus is very voluminous and 

 fills almost all of the postacetabular region, its folds being very numerous 

 and distinct in the living specimen. A considerable mass of ova lies in 

 front of the ventral sucker. The eggs are small and there seems to be 

 some variety in the size. The excretory vessels were conspicuous in the 

 living worm and are still more easily seen than usual in the mounted 

 specimen. Inflated vessels are to be seen on each side of the esophagus, 

 and a longitudinally ribbed posterior vessel, though less easily seen than 

 in the living worm. The length in life was 2.10 and the breadth 0.90, 

 and the ova 0.034 by 0.020. 



Dimensions in balsam: Length 1.82; breadth 0.64; neck 0.66; oral 

 sucker 0.25; pharynx, length 0.07, breadth 0.08; ventral sucker 0.43; ova 

 largest 0.037 by 0.024, smallest 0.027 by 0.015. 



Host, Ocyurus chrysurus: July 15, 1908, 1 fish, 1 distome. 



Two distomes from Hoemulon macrostomum are referred to this 

 species with much hesitation, not only with regard to placing them in 

 this species, but as to whether they themselves should be placed in the 

 same species. 



These distomes are figured (figs. 103, 104) and may be seen to be 

 quite different in shape. The differences, however, do not appear to 

 me to be sufficient to justify their separation at present. The esophagus 

 and intestine in fig. 104 were very indistinct, and the apparent shortness 

 of the esophagus may be due to the contracted condition of the neck. 

 The metraterm lay on the anterior border of the cirrus-pouch instead 

 of on its caudal border, as in the specimen figured in figs. 102 and 104. 

 Since all the specimens were more or less flattened and consequently 

 somewhat distorted, the difference may be due to forced displacement. 



Dimensions of the specimen shown in fig. 103, mounted in balsam: 

 Length 1.68; breadth 0.58; neck 0.72; oral sucker 0.21; pharynx, length 

 0.06, breadth 0.08; ventral sucker, length 0.35, breadth 0.32 ; ova, largest 

 0.044 by 0.024, smallest 0.034 by 0.024, usual size about 0.040 by 0.020. 



Host, Hcemulon macrostomum: July 10, 1906, 2 distomes. 



A distome found in the cow pilot (Abudefduf saxatilis), July 15, 

 1906, appears to belong here. 



The stained and mounted specimen is little more than a mass of ova. 

 The following features, however, can be recognized: The testes are 2, 

 nearly opposite each other at about the posterior third, each near the 

 lateral margin of its side. The ovary is near the middle line, a short 

 distance in front of the testes. The vitelline glands consist of a few granu- 

 lar masses along the margins extending from about the level of the ovary 



