6 G-H Canadian Arctic Expedition, 1913-18 



Opening of excretory cisterns dorsal and behind and in line with the neck 

 at the level of the prostatic portion of the cirrus-sac. One main excretory canal 

 on each side of the body a short distance lateral to the intestinal coeca. 



Hermaphroditic duct, about 0-6 mm. in length, openp close behind the left 

 anterior adhesive organ at the neck; into its proximal end the uterus opens 

 slightly ahead of the cirrus. Opening of the vagina ventral and 0-85 to 0-95 

 mm. directly behind the common genital opening. 



Testes at the middle of the body, irregularly elliptical in shape with crenate 

 margins, 1 • 80 to 2 ■ 28 by 1 • 30 to 1 ■ 65 mm. in dimensions, longer axes parallel to 

 longitudinal axis of body. Vas deferens 0-13 mm. in diameter when filled with 

 sperms. Cirrus-sac pyrif orm, • 84 to • 88 by • 45 to ■ 56 mm. in dimen^sions ; 

 prostatic reservoir ellipsoidal, 1 ■ GO to 1 • 50 by ■ 65 to ■ 95 mm. 



Ovary median, ovoid in shape, 0-75 to 0-95 mm. in transverse diameter; 

 ova from beginning of oviduct 35 to 40/i in diameter. Oviduct 0-16 mm. in 

 diameter at its point of exit from the ovary which is slightly to the right of the 

 median line, narrowing to 20/i where it is joined by the common vitelline duct 

 and to 25/i where the seminal vesicles, five or six in number, unite with it. Shell- 

 glands equidistant from the seminal vesicles and the ootype. Latter spindle- 

 shaped, 0-15 mm. in diameter. Bulb of uterus 1-0 mm. in diameter. Vitelline 

 reservoir subspherical, 0-65 to 0-80 mm. in diameter, pressed close to the anterior 

 border of the ovary slightly to the left of the median line; common vitelline 

 duct 35/i in diameter. Vagina arises from the left antero-lateral margin of the 

 vitelline reservoir. 



Eggs, tetrahedral, with long slender filaments. 



Habitat. — Skin of Hippoglossus hippoglossus (L.), the halibut; La Have 

 island, Nova Scotia, collected by C. H. Young. 



The above comparatively lengthy diagnosis of this form is given not only 

 for the sake of bringing together its main specific characters, which are somewhat 

 scattered throughout the literature, but in order also to include some new meas- 

 urements and diagnostic differences. No one seems to have pointed out clearly, 

 for instance, that the anterior pair of hooks of the posterior sucker protrude 

 considerably from the ventral surface of the organ. Consequently figure 2 is 

 here given to show this feature in lateral view. Figure 1 shows the hooks in 

 ventral view. It will be noted that in both figures they are inclined at an angle 

 of about 45 degrees to the median sagittal plane. Furthermore, so far as I have 

 been able to ascertain, the dimensions of the egg have, unfortunately, not been 

 given; but, owing to the fact they they are laid singly and that the material 

 studied was not in the best state of fixation and preservation, I am only able to 

 say that they are, as in other species of the genus, tetrahedral in shape and 

 each provided at one corner with a long slender filament. 



Order II Malacocotylea Monticelli 1892 



Suborder Pbosostomata Odhner 1905 



Family FASCIOLIDAE Railliet 1895 



Subfamily BRAGHYCLADIINAE Odhner 1905 



Genus Orthosplanchnus Odhner 1905 



Orthosplanchnus arcticus Odhner 1905 



(Fig. 3) 



1905: Orthosplanchnus arcticus, Odhner 1905: 339 



(Type host, Erignathus barbatus (Erxleben), bearded seal, west coasts 

 of Greenland and Spitzbergen) 



Specific diagnosis. — -With the characters of the genus. Small trematodes 

 from 3 • 5 to 7 mm. in length and • 70 to 1-15 mm. in breadth. Maximum width 



