TREMATODES FROM FISHES — LINTON 17 



Genus PLEUROCOTYLE Gervais and van Beneden, 1859 



PLEUROCOTYLE SCOMBRI (Gervais and van Beneden) 



Plate 16, Figures 210-214 

 See Stiles and Hassall, U. S. Hyg. Lab. Biill. 37, p. 346, 1908, for references. 



A trematode from the gills of the chub mackerel {Pneumatophortts 

 grex) , collected August 9, 1908, is referred to this species (U.S.N.M. 

 No. 8160). 



The worm is divided by a constriction into two parts, an anterior 

 lanceolate and a posterior clavate portion. The posterior portion 

 carries four conspicuous suckers, from 0.2 to 0.4 mm. in diameter, 

 in a longitudinal row. The first three suckers are longer than broad, 

 the fourth is broader than long. Behind the fourth sucker there is a 

 fifth minute sucker, about 0.04 mm. in diameter. It lies 0.15 mm. be- 

 hind the fourth sucker, and about 0.03 mm. from the posterior margin 

 of the sucker-bearing portion. The two suckers at the anterior end 

 are longer than broad, the pharynx is at their posterior edges, and 

 there is a relatively long esophagus. The intestine is profusely 

 branched, the branches beginning in front of the point of forking. 

 The intestines continue into the posterior, sucker-bearing portion. 

 The genital cloaca is about halfway between the pharynx and the 

 forking of the intestine. It is armed with a cluster of hooks, which 

 were somewhat broken and disturbed. These hooks appear to have 

 a large basal portion terminating at the anterior end in a small, 

 recurved claw. The basal portions together form an oval-elliptical 

 structure about 0.08 mm. in length and 0.05 mm. in diameter. The 

 ovary lies near the right side of the median line, 1.26 mm. in front 

 of the constriction; testes confined to narrow median space, about 

 1 mm. in length, behind the ovary. The vitellaria begin a short dis- 

 tance back of the forking of the intestine and extend into the sucker- 

 bearing portion, filling the body and obscuring the other genitalia. 

 The follicles are somewhat interrupted in the vicinity of the suckers 

 but they continue on both sides to the posterior end. 



Dimensions in balsam: Length, 7.84 mm.; breadth, anterior 0.16 

 mm., middle 1.47 mm., near posterior end 1.26 mm. ; anterior suckers, 

 length 0.09 mm,, breadth 0.05 mm.; pharynx, length 0.09 nun., 

 breadth 0.084 mm.; length of sucker-bearing portion, 2.38 mm.; 

 breadth, at constriction, 0.7 mm., middle, and to near posterior end, 

 1.26 mm.; first three posterior suckers, each, length 0.42 mm., 

 breadth 0.23 mm. ; fourth posterior sucker, length 0.21 mm., breadth 

 0.3 mm. ; minute terminal sucker, diameter about 0.04 nam. 



155599—40 2 



