70 PROCEEDINGS OF THE NATIONAL MUSEUM vol.88 



These distomes from the cod are elongated, slender, with promi- 

 nent ventral suckers. Average of four : Breadth, 0.49 mm. ; breadth 

 of first testis, 0.31 mm. 



From conmion eastern stickleback : This distome was collected from 

 the stickleback on 10 dates in 6 different years, in the months of 

 April, May, June, and July. On all but one date the collections were 

 made by Vinal N. Edwards. Distomes not numerous, 114 in all. 

 Over 200 fishes were examined. The largest number recorded for any 

 date is 25, when 40 fishes were examined. They range in length from 

 3 to 7 mm. in formalin. Manj^ of them are turgid, with conical necks 

 reflected dorsally at right angles to the body. In some cases the vitel- 

 laria are not interrupted at the level of the testes. Ventral sucker 

 approximately twice the diameter of the oral sucker, and three times 

 that of the pharynx. Measurements, life: Length, 3 mm., breadth, 

 0.42 mm. ; breadth of oral sucker, 0.15 mm., of pharynx, 0.09 mm., of 

 ventral sucker, 0.36 mm. (U.S.N.M. No. 8234.) 



From the sea raven : Collected from this host by Vinal N. Edwards 

 on 9 dates in 6 different years, in the months of January, April, 

 May, October, and December. The record shows that 16 fishes were 

 examined, from which 198 distomes were obtained. The greatest 

 number recorded from one fish is 117, collected on May 15, 1916; 

 the smallest for any one date is one on December 24, 1912, when three 

 fishes were examined. A distome, one of a lot of 16 collected on April 

 26, 1915, is exceptional in that, in spite of its size (length, 9 mm., 

 maximum diameter, 1.12 mm.) no ova are present. It would appear 

 that something had gone wrong with its egg-making mechanism. 

 In front of the ovary there is a great deal of granular material as- 

 sociated with the follicles of the vitellaria. Masses of this material 

 lie in front of the vitellaria, extending on the left side to the middle 

 of the ventral sucker, and on the right side to its anterior border. 

 (U.S.N.M. No. 8235.) 



While most of these distomes from the sea raven maintain a 

 breadth that does not vary greatly, the point at which the greatest 

 breadth occurs varies. Thus, the greatest breadth in some is at the 

 level of the testes, in others behind the testes, and in yet others be- 

 tween the ovary and ventral sucker. There is great variation also 

 in the ratio of length to breadth. This is due to the fact that living 

 specimens, in which the breadth may be as great as half the length, 

 if placed in fresh water, or weak formalin, may become elongated, 

 slender, and cylindrical, often with neck reflected and ventral sucker 

 projecting. The cirrus is smooth, and when exserted is seen to have 

 a bulbous base. The vitellaria, in extended specimens, are interrupted 

 at the level of the testes; in contracted specimens they may be con- 



