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THE ROYAL SOCIETY OF CANADA 



The following table gives the measurements of the largest speci- 

 mens at hand, excepting those from the last named host, which were 

 all immature: 



The following measurements are applicable to (1) and (2), res- 

 pectively, from the Maskinonge : Ovary from the anterior end, 30, 

 30 • 5, first testis, 32, 32-5, second testis, 35, 36, while in both the centre 

 of the acetabulum is 4-5 from the anterior end. All of the measure- 

 ments given for the examples from the Maskinonge warrant the view 

 that they are identical with Stafford's Megadistomum longum Leidy, 

 but after a careful comparison of the smallest with those from the 

 Pike, I am inclined to the view, also expressed by Odhner (18, pp. 

 520-21), that this species is only to be considered as a very large 

 Azygia lucii. The smallest specimen showing eggs (not yet mature) in 

 the uterus was 8mm. in length, while that from the Pike was 6mm. in 

 length, but this characteristic ("Eiproduktion") seems to be by no 

 means constant, since many longer specimens, for example. No. 2. 

 under L. liicuis in the above table, shows less mature eggs than those 

 in the 6mm. example. On the other hand, examples of intervening 

 lengths may have their uteri distended with ripe eggs! Those from the 

 Pickerel, comparable to Stafford's Mimodistomun angusticaudiim 

 were so poorly preserved and so contracted longitudinally that I do 

 not feel justified in separating them from A. lucii. The acetabulum 

 is situated at the junction of the anterior and middle thirds of the 

 body, and the ovary and testes are crowded together posteriorly as 

 in several of Goldberger's species. All from the Trout are immature, 

 including the largest, 11mm. in length, — a statement which also ap- 

 plies to those from the Small-mouthed Black Bass. A number from 

 the Pike show the globose excretory vesicle of Goldberger's A. hulbosa 

 (4, pp. 22-26) ; but this character, together with the length, extent and 

 "breaking" of the vitellaria are of such a variable nature as to lead me 



