SEA-FISHERIES LABORATORY. 319 



G. virens, Molva vulgaris, 



G. melanostomus, Pleuronectes limandoides, 



G. merlangus, Rhombus laevis, 



G. pollachius, Hippoglossus maximus, 



Mursena anguilla. 



This extensive list of hosts indicates that the immature 

 form of the worm is to be found in some animal or animals 

 which are very widely distributed, and Pratt* has 

 described an immature trematode from copepods which 

 is most probably the young of T). cifpendiculatum. In 

 the small flat fish referred to in the present paper, 

 copepods principally were found in nearly every specimen 

 examined, 



Distomum gulosum, Linton.f — Fig. 23 C. 



Host : Mackerel, off Walney Island, July, 1905. 



About half-a-dozen specimens of an appendiculate 

 Distome were found by A. Scott in a mackerel dissected by 

 him, and I refer these worms to the species described by 

 Linton as D. gulosum, from the Butterfish, Rhombus 

 triacanthus, of the Wood's Hole region. The principal 

 characters made use of by Linton in his diagnosis are 



(1) the relative sizes of the oral and ventral suckers, and 



(2) the tubular form of the vitellaria. 



The measurements of the specimens figured here 



are : — 



Length : 10 mm. ; 



Diameter at ventral sucker : l'l mm. ; 

 Diameter of oral sucker (transverse) : 0*6 mm. ; 

 Diameter of ventral sucker (transverse) : 

 0*5 mm. ; 



* Zool. Jahrb., xi., 1898. 



f Bull. U.S., Fish Comm., vol. 19, for 1899-1901, p. 454, 

 PI. 28, figs. 315-316. 



