66 Papers from the Marine Biological Laboratory at Tortugas. 



pharynx usually about half the diameter of oral sucker. There is a dis- 

 tinct prepharynx and an esophagus. The proportions of the prepharynx 

 and esophagus are variable (figs. 156, 157). The forking of the intes- 

 tines is, in some cases, on a level with the ventral sucker, in others 

 behind it. The rami of the intestines reach nearly to the posterior end 

 of the body. Genital aperture in front of ventral sucker and near it. 

 There is a conspicuous cirrus and cirrus-pouch, the latter inclosing the 

 convoluted seminal vesicle and prostate, extending dorsal to the ventral 

 sucker and behind it. There is but one testis, which is relatively large, 

 especially in the younger adults, and is situated about the posterior 

 third. The ovary lies a short distance in front of the testis. It is an 

 oval or subspherical body, and, like the testis, lies on the median line. 

 It is preceded by the conspicuous shell-gland, on the right and ventral 

 side of which there is a seminal receptacle. The folds of the uterus lie 

 between the ovary and the ventral sucker. The vitelline glands are 

 diffuse and lie along the margins at the posterior end, and are scattered 

 through the median region of the body. They extend forward about to 

 the ventral sucker. 



Host, Teuthis hepatus: 



1907, July 1, 1 fish, 3 distomes. 



1908, July 11, 1 fish, 14 distomes; July 13, 3 fish, 17 distomes; July 

 15, 1 fish, 9 distomes. 



In some the spinose cuticle was separating from the body; intes- 

 tines frequently dark brown. In one lot there were thought at first to 

 be three distinct species: (1) Translucent, plump, cylindrical, old speci- 

 mens. Dimensions, lying free in water: Length 2.66; breadth 0.70; 

 oral sucker 0.21 ; pharynx 0.07; ventral sucker 0.21 ; ova 0.042 by 0.024. 

 (2) Opaque, white, thickish. Dimensions, compressed: Length 2.87; 

 breadth 0.97; oral sucker 0.21; pharynx 0.08; ventral sucker 0.26; ova 

 0.045 by 0.027. (3) Flat, thin, faint greenish-yellow, translucent, appar- 

 ently younger forms of the foregoing but with fewer ova. In these 

 there was a great variety of outline, especially of the anterior end, taper- 

 ing, bluntly rounded, and a few knobbed by a constriction just behind 

 the oral sucker. The opaque forms, before compression, were often trun- 

 cate and had a strong tendency to slough off the epidermis. 



One slender, immature distome had the following dimensions: Length 

 1.50; breadth 0.40; oral sucker 0.12; pharynx 0.06; ventral sucker 0.10. 



Host, Teuthis cceruleus: 



1908, June 27, 1 fish, 1 distome; July 6, 1 fish, 5 distomes. 



Dimensions, life, flattened: Length 3; breadth not recorded; oral 

 sucker 0.27; pharynx 0.14; ventral sucker 0.27; ova 0.04 by 0.02. 



DERADENA gen. nov. 



Etymology: dipy, neck; a^'v, gland. 



Body smooth. Vitellaria diffuse, posterior, and lateral, in most 

 cases entirely behind ventral sucker and not reaching to the anterior 

 border of the ventral sucker in any of the species here described. Testis 

 one, oval, or somewhat triangular in outline, on median line towards 

 the posterior end of the body; ovary oval, not lobed, in front of testis; 



