10 G-H Canadian Arctic Expedition, 1913-18 



tides, leaving free more or less circular areas above and below the uterus and 

 somewhat smaller than the uterus; 1,500 to 2,000 per segment; ellipsoidal m 

 shape with the longitudinal axes dorsoventral, slightly compressed anteroposter- 

 iorly; average length, width and depth, 40, 75 and 85ai, respectively. Common 

 vitelline duct short, expands to form a reservoir 35 to 40m in diameter just before 

 joining the oviduct. Shell-gland diffuse, some of its cells extendmg to the 

 ventral musculature. Uterine rosette circular or eUiptical in surficial view, 

 0-85 to 1-20 mm. in length, 1-20 to 1-70 in width and 0-50 to 0-60 m depth, 

 composed of 8 to 10 coils on each side of the median line, the most anterior pair 

 of which pass forward on each side of the cirrus-sac. In the oldest segments the 

 walls of the uterus break down, thus converting the rosette into a more or less 

 undivided sac. Opening of uterus at the centre of the proglottis, 70 to 75^ in 

 diameter. 



Eggs, brownish yellow in colour, eUipsoidal in shape, 56 to 59/i in length by 



37 to 39m in diameter; operculum 15 to 20m in diameter, shell 2-5 to 2-8m in 



thickness; boss at the end opposite that bearing the operculum, 4m in diameter. 



Type host. — Corvus corax principalis Ridg., the northern raven, in the 



intestine. 



Type locality. — Bernard harbour, Northwest Territories, Canada. 

 Collected by Mr. Frits Johansen, August 29, 1915. 



Cotypes are deposited in the Victoria Memorial Museum, Ottawa, Canada, 

 (AnneUds, etc., catalogue No. 76), and in the collection of the writer at Chicago, 

 U.S.A. 



This form obviously does not belong to any of the three species of Diphyllo- 

 bothrium which have been described from birds in Europe, namely, D. ditremum 

 (Creplin), D. dendriticum (Nitzsch) and D. fissiceps (Creplin), the first of which 

 was reported by Linstow (1905: 16) from a young male Larus glaucus F. from 

 West-Tajmyr, Middendorffsbay. However, it resembles in many respects 

 Dibothrium cordiceps Weinland as described by Linton (1891) from Pelecanus 

 erythrorhynchus at Yellowstone Lake. The superficial characters and measure- 

 ments of the two forms agree fairly well, while the anatomy of D. cordiceps is 

 undoubtedly that of a species of Diphyllobothrium — as suggested by Ward 

 (1918:432) — very close to if not indentical with this cestode. In D. canadense, 

 however, I saw no distinct expansion of the vagina at its beginning to form an 

 outer seminal receptacle, as described by Linton, nor eggs with measurements 

 as large as those he gave, namely 70 by 35m- Consequently until D. cordiceps is 

 removed from the species inquirendae, it seems advisable to record this form 

 under a new name. 



Diphyllobothrium cordatum (Leuckart 1863) 



This species has been sufficiently described for diagnostic purposes by 

 Zschokke (1903:4-6). 



Seven specimens were found in company with D. lanceolatum and Pyramico- 

 cephalus phocarum, the next two species, in the lot of material labelled, "From 

 the intestinal channel of Phoca [Erignathus] barbata, Bernard harbour. North- 

 west Territories, July 4, 1915, C.A.E. Station iOt,u." 



The three largest specimens, somewhat larger than those described by 

 Zschokke, had the following dimensions: 136 mm. in length by 4 in width, 140 

 by 6 and 154 by 6-5. The scolices were somewhat smaller, being only 1-3 mm. 

 in length and depth as compared with 1 ■ 8 and 1 • 8 given by Zschokke and 2 and 

 2 by other writers. Including the two or three smallest and most posterior loops 

 of the uterus there were 8 to 10 loops on each side of the median line rather than 

 6 to 8; and the eggs measured 70 to 72m by 50m in alcohol and 62 to 68 by 41 

 to 45m in synthetic oil of wintergreen in which the specimens studied were 

 cleared. These data indicate, incidentally, the marked variability in the shape 

 and dimensions of the eggs after complete dehydration and the consequent 



