TKEMATODES FROM FISHES — LINTON" 



67 



Six (U.S.KM. No. 8229), collected May 4, 1914, from the tautog. 

 Largest, in formalin : Length, 5 mm. ; breadth, 1.5 mm. In balsam, 

 largest, length, 3.92 mm.; breadth, 1.12 mm.; smallest, length, 2.8 

 mm., breadth, 1 mm. Measurements in balsam: Length, 3.82 mm.; 

 breadth, 1.06 mm. ; breadth of oral sucker, 0.21 mm., of ventral sucker, 

 0.39 mm.; pharynx, length, 0.11 mm., breadth, 0.14 mm.; length of 

 esophagus, 0.14 mm. ; breadth of first testis, 0.14 mm. ; ova, 0.075 by 

 0.039 mm. Average of six : Breadth, 0.95 mm ; breadth of first testis, 

 0.32 mm. Vitellaria extend to ventral sucker, uninterrupted at level 

 of testes. 



PODOCOTYLE OLSSONI Odhner 



Plate 1, Figures 8-12 



Distomnm simplex Rudolphi, Linton, Proc. U. S. Nat. Mus., vol. 20, pp. 525, 



526, pi. 47, figs. 3-7, 1989; Bull. U. S. Fish Comm. for 1899, pp. 436, 468, 



475, 485, figs. 331, 332, 1901. 

 Distomnm vitellosum Linton, Bull. U. S. Fish Comm. for 1899, p. 464, 1901. 

 Podocotyle olssoni Odhner, Trematoden des arktischen Gebietes, Fauna Arctica, 



vol. 4, p. 327, 1905.— Mantee, Illiuois Biol. Mon., vol. 10, No. 2, pp. 208, 209, 



fig. 50, 1926. 



The principal points in which this species differs from P. atomon 

 are its relatively shorter esophagus, the much longer cirrus pouch 

 and seminal vesicle, and the greater breadth of the testes as com- 

 pared with the breadth of the body. The vitellaria are usually inter- 

 rupted at the level of the testes in P. olssoni, while they are, as a rule, 

 continuous in P. atomon. 



Thus, in P. olssoni the length of the esophagus seldom equals that 

 of the pharynx, the seminal vesicle may extend back of the ventral 

 sucker as much as halfway to the ovary, and the testes are relatively 

 much larger than they are in P. atomon. 



An average of 13 of each species showed for P. atomon: Breadth 

 of body, 1 mm., of first testis, 0.31 mm.; for P. olssoni'. Breadth of 

 body, 0.6 mm., of first testis, 0.3 mm. That is, for these specimens 

 the breadth of the tests was one-third the breadth of the body in 

 P. atomon. and one-half in P. olssoni. 



Table 16. — Comparison of average measurements in Podocotyle atomon and, 



P. olssoni 



