1893.] DR. p. soKsnfo on distomes.' 497 



Distome belongs to the subgenus Echinostomum, Dujardin, the oral 

 sucker being siurounded by a disk bordered by a circle of spines. 

 Dr. L. drley, who some years ago published an account of the 

 Nematodes from the collection of Prof. Siebold in the Museum \ 

 has not mentioned there the supposed Ojiliiostomum, therefore we 

 may fairly infer that he had not examined it. 



In the unique specimen of the worm in question, notwithstanding 

 its rather bad condition, the following characters may be verified : — 

 Body flat, elongated, rather narrowed behind ; length 7 millim., 

 breadth 2 mdlim., with the greatest diameter corresponding to the 

 ventral sucker, which is larger than the oral sucker. The latter 

 surrounded by a triangular disk, bordered by spines. The number 

 of these latter appeared to me to be 24, comprising the 4 lateral 

 and inferior larger. A darker spot behind the ventral sucker is 

 due to the oviduct being full of eggs, which are of large size and 

 not less than 100 micromillim. in length. Tolk-glands rather 

 voluminous from the ventral sucker to the posterior end. Two 

 oval testes at the beginning of the posterior half of the body, one 

 behind the other. Ovarium anterior to the testes. 



With such characters I suspected that the Trematode was D. 

 trigonocejihalum, the ordinary Echinostomum found in mammals ; 

 but before pronouncing myself definitely, I \nshed to compare the 

 characters of the specimen in question with those of B. trigono- 

 mphalum. My short visit to the British Museum not allowing me 

 to make this comparison there, 1 made it when I returned home. 

 I found in the collection of the Zoological Museum of Pisa no less 

 than four bottles containing D. trigonocejyhalum obtained from three 

 different species of Mammals, viz. Mustda foina, M. putorius, 

 and 2Ieles europcmts. Thus I had plenty of material to give me a 

 clear notion of the characters and different appearances of D. 

 trirfonocephalum from various sources. I am now able to say that 

 the specimen of the Trematode of Plecotus commiiiiis in the collec- 

 tion of the British Museum is, both as regards size and confor- 

 mation of the body, as well as the disposition of the spines around 

 the oral sucker, much like D. trigonoceplialum. There is also a 

 similarity in the eggs. Only the testes of the Echinostomum in 

 the British Museum appear to be situated rather more behind ; 

 but I do not attach much importance to this. Indeed the number 

 of the spines round the head given by von Linstow - and verified 

 in many specimens by myself is 26 instead of 24. But it is 

 possible that I mistook the number when examining the specimen. 

 I think, therefore, that the specimen in the British Museum is 

 nothing else but D. trigonocephalum. In his ' Compendium,' 

 Linstow does not make mention of such a Trematode as parasitic 

 in any Bat. But D. trigonocephalum has been found in Erinaceus 

 eurojJCBUs, and it is rather interesting to know that it may also be 

 parasitic in a Bat. Thus it is found in animals belonging to no 



1 Ann. & Mag. Nat. Hist. sev. 5, vol. ix. p. 301 (1882). 

 ■' Troschel's Avchiv, i. p. 106 (1873). 



