STUDIES ON THE ÉCTOPARASITIC TREMATODES OF JAPAX. \J() 



occasion I kept a few specimens of 21. caiuhta jast taken from a very 

 fresli fish, on a glass slide covered with sea-water, these executed 

 what Has well calls "looping" movements (spannende Bewegung) 

 like those of the leech. The worm, namely, first attached its anterior 

 end to the slide, apparently l)y means of the anterior suckers, and 

 dra^-ofino: after it the hinder part of its bodv, attached the caudal disc 

 close up to the anterior end by means of the posterior suckers, the 

 body in the meanwhile being folded on itself on the ventral side so 

 as to form a loop ; the worm then let go the anterior end and stretch- 

 ing its body, again attached it to the slide, detaching at the same time 

 the posterior suckers, which were then again brought close uji to the 

 anterior end, and so on. The looping movement is slow in Micwco- 

 tijlc, but in Monocotijle it is very rapid and energetic and is just like 

 that of an excited leech. The worms moved quite rapidly while on 

 the host, but when I transferred them to a watch-glass filled with sea- 

 water, they at once began wandering about so quickly that each 

 looping movement could only just be distinguished, and now and then 

 they groped about with the anterior extremity of their body, thus show- 

 ing apparently signs of surprise. The posterior sucker of this worm, 

 containing as it does the striped muscular fibres already described, 

 adheres very strongly to external objects — not only to the surflice of the 

 mouth-cavity but also to a smooth surface such as that of the watch- 

 glass. Tristomum sinuatum executes locomotion quite rapidly but 

 still much more slowly than Monocotijh. The comparatively small 

 posterior sucker of this worm is capable of adhering very tightly to 

 the surface of the gill. When the worm advances its anterior suckers 

 to attach them to the substratum, it «tretches out its body to such an 

 extent that it becomes much elono-ated and its breadth is reduced to 



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about one-third its length. Ijesides the looping movement which all 

 the three species above mentioned are able to execute, I have also 



