48 Papers from the Marine Biological Laboratory at Tortugas. 



end, soon dividing into two branches which lie ventrally and laterally 

 and extend as far forward as the testes. The shape of the excretory 

 vessel is thus like the letter Y. The ova are pyramidal or ovate, with 

 rather thick shells. 



Dimensions in balsam: Length 1.50; breadth, anterior 0.18, middle 

 0.45, posterior 0.10; neck 0.70; oral sucker, length 0.21, breadth 0.18; 

 pharynx, length 0.08, breadth 0.06; ventral sucker 0.16; ova 0.031 by 

 0.019. 



Host, Angelichthys isabelita: 



1906, July 10, 1 fish, 1 distome. 



1908, July 3, 1 fish, 3 distomes. 



Host, Pomacanthus arcuatus: 



1906, July 18, 1 fish, 5 distomes. 



1907, July 3, 1 fish, 12 distomes; July 11, 1 fish, 238 distomes; July 

 15, 1 fish, 150 distomes. 



1908, June 29, 1 fish, 93 distomes; July 1, 1 fish, 39 distomes; July 

 3, 2 fish, 68 distomes; July 4, 2 fish, 28 distomes; July 5, 2 fish, 

 2 distomes; July 7, 2 fish, 6 distomes. 



The color of these distomes in life in some cases was red. The shape 

 varied from long oval to short oval. Measurements of ova showed a 

 variation in the same individual of 0.037 D Y o- OI 7 an d 0.031 by 0.019. 

 The length in one of the smaller lots varied from 0.84 to 1.68. 



Diplangus paxillus gen. et sp. nov. (Figs. 94-101.) 

 Etymology: 8mX6os t double; ayyos, vessel. 



This distome is characterized by its cylindrical body, which is atten- 

 uate posterioi'ly, and by its prominent ventral sucker. Although found 

 on many occasions, my material does not allow details of structure to be 

 made out with entire satisfaction. 



Body cylindrical, smooth, thickest at ventral sucker, neck abruptly 

 conical, body usually attenuate behind ventral sucker and tapering to 

 the posterior end. Oral sucker subterminal; pharynx adjacent to oral 

 sucker or separated from it by a very short prepharynx ; ventral sucker 

 larger than oral, prominent, almost pedicelled in some; esophagus short; 

 intestinal rami extending a little more than half-way to the posterior 

 end. Genital aperture median, ventral to pharynx; cirrus short, slender; 

 seminal vesicle in two parts, a posterior prostatic portion with large 

 cells in the wall and an anterior globular portion with thinner walls 

 (sv and pr in figs. 94-100). The testes are 2, globular, near together, 

 one behind the other, and placed about half-way between the ventral 

 sucker and the posterior end. Ovary dorsal, a short distance in front of 

 testes; seminal receptacle immediately in front of ovary. The vitelline 

 glands are clustered lateral masses behind the ventral sucker and ex- 

 tending to the ovary. The folds of the ovary fill the body both in front 

 of and behind the testes; ova oblong-elliptical, the long diameter twice 

 the shorter. Numerous glandular cells in the neck are interpreted to be 

 yolk-forming. 



Host, Hasmulon macro sternum: 



1907, June 28, 2 fish, 1 distome. 



