DR. T. S. COEBOLD ON THE LABGE HUMAN FLUKE. 285 



On the supposed Earity, jSTomenclature, Structure, AfBnitiea, and 

 Source of tlie large human Fluke {Distoma crassum, Buisk). 

 By T. Spencer Coebold, M.D., F.E.S., F.L.S., Lecturer on 

 Parasitic Diseases. 



[Eead February 10, 1875.] 



It will be within the recollection of some of the senior members 

 of the Society that about thirty years ago Professor Busk disco- 

 vered fourteen large flukes in the duodenum of a Lascar who died 

 at the Seamen's Hospital. Not only were these parasites cor- 

 rectly regarded as new to science at the time, but, what is more 

 remarkable, no second instance of the occurrence of this entozoon 

 has since been placed on record. To be sure, there are several 

 human parasites that have only once been observed; but these 

 instances refer, for the most part, to minute helminths, such as the 

 dwarf tapeworm {Tcenia nana) and the almost microscopic fluke 

 known as the Distoma heteropJiyes. It is therefore, I repeat, 

 rather strange that during the interval elapsing from the winter- 

 of 1848 to the spring of 1874, this comparatively large Trematode 

 should not have been again encountered — and the more so, since 

 our professional friends stationed in India, and throughout the 

 East generally, have of late years shown great activity in search- 

 ing for entozoa. 



In reference to the assumed rarity of the parasite, it will not be 

 out of place to refer to other instances of a similar kind aflTecting 

 animal hosts. I will adduce only two cases, in both of which the 

 entozoa, though now known to be abundant, were for a long 

 time overlooked, and consequently supposed to be extremely rare. 



In the year 1858 I discovered a small fluke in the liver-ducts 

 of an American red fox {Canis fulvus) that had died at the Zoolo- 

 gical Society's Gardens ; but no second instance of the occur- 

 rence of this parasite {Distoma conjunctwm) was recorded until the 

 year 1871, when Dr. Lewis found great numbers infesting the 

 pariah dogs of India. The second and far more striking instance 

 of verification after a long interval of time is that ot SfepAanurtis 

 dentatus. This rather large Nematode was originally discovered 

 by Natterer at Barra do Eio Negro, Brazil, in J.834. He found 

 it infesting a Chinese variety of the common hog. It was shortly 

 afterwards described and figured by Dicsing ; and nothing could 

 exceed the accuracy of the description given by the Vienna hel- 



