Some undescribed Tromatodes. 40l 



considerable interest both from a morphological point of view — in 

 its large size and cliaracteristic structure, and from a physiological 

 point of view — in the probability of its function. If it is as it appears 

 in my mounted specimen, I think it may well count as new to Trema- 

 tode Helmin thology. The scantiness of my material, however, compels 

 me to accept only with some reservation any view as to the uses of 

 the Organ in question. 



The posterior end of the animal appears to be invaginated and 

 the cavity thus formed is continuous with the exterior through a nar- 

 rowed opening. The walls of this relatively large cavity are folded 

 longitudinally and its anterior end is pushed backwards to form a cup 

 which receives the blind ends of the intestine and some unditferentiated 

 meristem parenchyma. I suppose that two lateral excretory tubes 

 open into this cavity behind the intestine and it seems likely that this 

 whole structure is to be considered as au enormously enlarged ex- 

 pulsion canal, The cuticle in some other Trematodes continues through 

 the porus excretorius on to the inner surface of the expulsion canals, 

 but here the thick muscular wall also appears to be continued. In a 

 section falling through the anterior wall of this organ are apparently 

 two openiugs, but, on account of the folds and creases of its inner 

 walls, I could not be certain that they are the mouths of the excretory 

 tubes. A longitudinal section here would be very instructive. 



The whole structure impressed me from the first with the idea 

 that we have to do here with a specialization of the posterior end 

 of the excretory System in adaptatiou to the requirements of a para- 

 sitic animal which has acquired the habit of temporarily quitting one 

 host and leading for a time a pelagic existence by forcibly squirting 

 water from its expulsion canal in a fashion similar to what takes place 

 in the jelly-fishes and squids until perchance it is thrown agaiüst a 

 new host. While I observed it living, I saw no such Performance 

 although it was very active in squirming, fixing and releasing its 

 suckers etc. and it is possible that the structure in question may have 

 quite a different function. 



Should it be found capable of the locomotion I suggest, it will be 

 observed that the animal is pelagic; but it must also be for a time 

 ectoparasitic, for which mode of life its suckers are well suited; and 

 further, as is indicated by the structure of its cuticle, it is an endo- 

 parasite, capable of wandering through the softer tissues of the animal 

 it infests. 



