Helminth Fauna of the Dry Tortugas. 39 



ovary is small, subspherical, situated near the median line, a little to the 

 right and a short distance behind the ventral sucker. The shell-gland 

 lies on the antero-dorsal border of the ovary and the seminal receptacle 

 a httle in front of the ovary and to the right of the shell-gland. The 

 testes were subglobular in Hfe, ovate-elliptical in the mounted specimen. 

 They lie close together on the median line, one behind the other, a short 

 distance back of the ovary. The vitelline glands are diffuse and occupy 

 nearly the whole space marginal and posterior to the ovary and testes, 

 but do not extend quite as far forward as the posterior border of the 

 ventral sucker. The ova are few, relatively large, and lie between the 

 anterior testes and the ventral sucker. The metraterm passes dorsad 

 of the cirrus-pouch and opens at the common genital aperture. The 

 excretory vessel was not seen, but two patches of fine granular, black 

 pigment lying lateral to the prepharynx are probably in the lateral ex- 

 cretory vessels of the neck. 



Host, Kyphosus sectatrix: July 5, 1908, i distome. 



Dimensions in life: Length 3; breadth 0.83; diameter of oral sucker 

 0.38, pharynx 0.38, ventral sucker 0.28; ova 0.06 by 0.03. 



Didymorchis latus gen. et sp. nov. (Figs. 65, 65a.) 

 Etvmology: o:''J'v'"v', twin; ^v'/'v", testicle. 



Body broad-oval, nearly as broad as long, or breadth equal to about 

 three-fourths of length; the diameter of ventral sucker is about three 

 times that of the oral. There appears to be a short prepharynx but no 

 esophagus. The intestinal rami extend to the posterior end. Genital 

 aperture median at base of pharynx; cirrus-pouch short, lying at the 

 anterior border of the ventral sucker, and containing the meager prostate 

 and seminal vesicle which is, for the most part, a compactly folded tube. 

 Testes 2, opposite and adjacent, somewhat triangular in outline, and 

 lying near the posterior end. Ovary subglobular, lying between the 

 posterior margin of the ventral sucker and the anterior margin of the 

 right testis; seminal receptacle on right dorsal border of ovary. The 

 vitellaria are diffuse and lie along the posterior and lateral margins, 

 extending to the pharynx. Transverse yolk-ducts lie along the anterior 

 border of the left testis dorsally and on the dorsal side of the ovary; 

 shell-gland dorsal to posterior edge of ventral sucker and along anterior 

 edge of seminal receptacle. The uterus is mainly on the left side between 

 the left testis and the anterior border of the ventral sucker. The metra- 

 term passes on the left of the cirrus-pouch to the genital aperture. 



Host, Calamus calamus: 



1908, June 29, 2 fish, i distome; July 11,5 fish, i distome. 



Length of first 2.03, breadth 1.54. The latter specimen was yellow- 

 ish in life. Its dimensions were: Length 2.24, breadth 2.38; oral sucker 

 0.35 ; pharynx 0.28; ventral sucker 1.36; ova 0.064 by 0.037. 



The dimensions of this specimen in balsam are: Length 2.17; breadth 

 1.46; neck 0.84; oral sucker, length 0.46, breadth 0.49; pharynx, length 

 0.42, breadth 0.24; ventral sucker, length 0.70, breadth 0.90; ova 0.061 

 by 0.034. 



