JOURNAL OF THE COLLEGE OF SCIENCE, TOKYO IMPERIAL UNIVERSITY. 



VOL. XXXIX., ARTICLE 4. 



Two New Trematodes of the Family 

 Gyrodactylidse. 



By 



Seitaro GOTO, 



Professor in the Science College, Imp. Univ., Tokyo, 



and 



Hajime KlKUCHI, 



Teacher in the Kawagoe Middle School, Saitama Ken. 



With two plates. 



i. Dactylogyrus inversus, n. sp. 



This new species of Dactylogyrus is quite common on the 

 gills of one of our most widely distributed food fishes, Lat'eolabrax 

 japonicus (Cuv. & Val.), and may be collected all the year round. 

 Two or three worms are usually found attached close together to 

 the same gill. Their movements are quick and active and consist 

 of alternate contractions and elongations of the body, at the same 

 time feeling about in various directions with their anterior ends; 

 but they mostly keep themselves attached to one spot by their 

 caudal disk, although they are able to execute leech-like loco- 

 motion. Full grown worms are 2.5 mm. long and 0.6-0.7 mm. 

 wide. As a rule smaller worms are found on smaller hosts. The 

 worms die rather soon when detached from the host; we have 

 been able to keep them alive in physiological salt solution only for 

 a single day; it was in autumn. 



The body is colourless except for the vitellarium, which is 

 faintly yellow and shows through very well; it is spatulate in 

 form, being broadest at the middle and well rounded both in front 

 and behind when contracted moderately, but is comparatively 



