TREMATODES FROM FISHES — LINTON 119 



very short; rami of intestine extend to posterior end of body. Gen- 

 ital pore behind oral sucker; cirrus pouch short, with thick walls, 

 partly overlapping anterior edge of ventral sucker ; testes obscured by 

 the ova, but appear to be not far back of the ventral sucker, and 

 nearly transverse; ovary behind testes, on right side of the median 

 line ; vitellaria two, opposite, behind the ovary and near the posterior 

 end; ova scattered through the postacetabular region, from near the 

 posterior end to the ventral sucker ; shells of ova not much collapsed. 



Measurements in balsam: Length, 1.05 mm.; breadth, at level of 

 oral sucker, 0.21 mm., at level of ventral sucker, 0.38 mm., maximum 

 0.39 mm. ; oral sucker, diameter, 0.17 mm. ; pharynx, diameter about 

 0.07 mm.; ventral sucker, length, 0.28 mm., breadth, 0.34 mm.; ova, 

 average of 10, 0.040 by 0.023 mm. 



Host. — Chinook salmon {Oncorhynchus tschawytscha) . 



Two distomes (U.S.N.M. No. 8318) found on slide with specimens 

 of GenavcTies infrmus. 



Measurements of smaller specimen : Length, 0.84 mm. ; breadth, at 

 level of oral sucker, 0.15 mm., at level of ventral sucker, 0.28 mm.; 

 diameter of oral sucker, 0.12 mm., of pharynx, 0.06 mm., of ventral 

 sucker, 0.23 mm.; ova, 0.039 by 0.039 by 0.018 mm., to 0.042 by 

 0.021 mm. 



Subfamily Hemiurinae Looss, 1899 



Genus HEMIURUS Rudolphi, 1809 



HEMIURUS APPENDICULATUS (Rudolphi) 



Plate 8, Figukes 68-74 



Distomum appendiculatnni Rudolphi, Linton, Bull. TJ. S. Fish Comm., fox- 1899, 

 p. 289, 1900; Hid., p. 415, 1901 (list of hosts with page references). 



The small appendiculate distomes referred to this species have been 

 found in many species of fishes in the Woods Hole region. 



Their frequent occurrence in young fishes which feed on the inter- 

 mediate hosts of this distome (copepods, etc.), and which themselves 

 in turn become the food of a variety of fishes, doubtless accounts for 

 the w4de distribution of the species. 



The following description from notes made on material from the 

 herring {Clupea harengus) applies in general to forms from other 

 hosts. Additional data will be found in the record of collections. 



Body more or less fusiform, crossed anteriorly by fine lines produc- 

 ing serrate margins. These annulations are rather faintly shown on 

 many of the smaller specimens. So far as my material shows, the 

 appendix, when fully extended, is about half the length of the body. 

 The oral and ventral suckers are near together, and the diameter of 



