186 THE ROYAL SOCIETY OF CANADA 



immediately ahead of the ovary. The latter was bilobed instead of 

 trilobed in one specimen. 



Only one young specimen was taken from a Butterfish. 



7. Hirudinella clavata (Menzies). 2, pp. 662-99; 11, pp. 539-40. 



Stomach of Thunnus thynnus (L.), Tunny or Albacore. Little 

 River, St. Mary Bay, N.S. 



Nine specimens, all from the stomach of one host, fixed and pre- 

 served in 5% formalin and consequently much contracted, especially 

 posteriorly, ranged in length from 3 to 21mm. The following measure- 

 ments of one specimen (Fig. 7) corresponding in width at the ventral 

 sucker to Linton's largest alcoholic specimen are here given, with 

 Linton's data in brackets, for the sake of comparison: Length, 13-5 

 (18) ; diameter of head, about opposite the middle of the oral sucker, 

 2-0 (1-75); diameter of body at ventral sucker, 4-5 (4-5), behind 

 ventral sucker, 4 • 2 (4 • 2) ; diameter of mouth, contracted in all examples 

 to a minute aperture, (1-75); length of acetabulum, 4-5 (5-5), width, 

 4-5 (4-5); length of aperture of ventral sucker, 1-36 (2-5), breadth, 

 1'14 (1*8). The measurements of the largest specimen at hand 

 (Fig. 8) are as follows: Length, 21; diameter of head, 2-8, of body at 

 ventral sucker, 6-3, behind ventral sucker, 6-0, at widest part, 7-3; 

 length of acetabulum, 7-3, width ,7-0; length of aperture, 3-0, width, 

 1-7. The average dimensions of the eggs were 0-036 X 0- 023mm. 

 as compared to 0-034 X 0-024 given by Linton. Owing to the great 

 degree of contraction in these specimens both the anterior and posterior 

 portions of the body were much wrinkled transversely, the latter, 

 however, much more so than the former (Fig. 8). Only a very slight 

 dorsoventral flattening was noticeable, and the arching was not marked, 

 even anteriorly. Furthermore, by reference to the figures it will 

 be seen that the dilatation of the hinder end of the body, as figured by 

 Darr, is only slightly indicated, this again on account of extreme 

 contraction. In one medium-sized specimen, dissected, the testes, 

 ovary and shell-glands were found very much flattened against each 

 other longitudinally close behind the acetabulum. 



8. Derogenes various (O. F. Mueller). 24, p. 961; 26, pp. 483-84. 



Stomach of Salmo salar (L.) ; intestine of Sehastes marinus (L.) ; 

 encysted on the viscera and in the muscles of small fish (determined 

 for me by Dr. Philip Cox as Clupea harengus L.) from the stomach of 

 the Salmon, Bay of Fundy, N.B. 



All of the encysted specimens at hand contain brownish-yellow 

 eggs but are very small, measuring 2-01 X 0-43mm. (at the aceta- 

 bulum). Those free in the stomach of the other hosts give quite 

 similar measurements. From their positions in the muscles of the 

 small herrings, especially when found far back near the caudal fin, one 



