1893.] DR. p. so:n-sixo on distombs." 497 



Distome belongs to the subgenus Echinostonium, Dujardin, the oral 

 sucker beiug surrounded by a disk bordered by a circle of spines. 

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

 Nematodes from the collection of Prof. 8iebold in the Museum \ 

 has not mentioned there the supposed Oi)liiostonium, therefore we 

 may fairly infer that he had not examined it. 



In the Linique specimen of the worm in ij[uestion, notwithstanding 

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

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

 breadth 2 millim., 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 tlie oviduct being full of eggs, A\hich are of large size and 

 not less than 100 micromillim. in length. ToUv-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. 

 trigoaocejiludum, the ordinary Echiaostomum found in mammals ; 

 but before pronouncing myself definitely, I wished to compare the 

 characters of the specimen in question with those of D. trigouo- 

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

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

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

 than four bottles containing D. tvvjoaocepluduin obtained from three 

 differeut species of Mammals, viz. MusteJa fuiua, J/, -putoriiis, 

 and Ifeles europceus. Thus I had plenty of material to give me a 

 clear notion of the characters and different appearances of D. 

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

 the specimen of the Trematode of Plecotus coimnuuis 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. trvjonocephalum. There is also a 

 similarity in the eggs. Only the testes of the Eclduostomuin 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 2(j 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. trigoiiocephalum. In his ' Compendium,' 

 Linstow does not make mention of such a Trematode as parasitic 

 in any Bat. But D. trhjonocephalum has been fouud in Erinaceits 

 cui'opceius, and it is rather interesting to know that it may also be 

 parasitic in a Bat. Thus it is found in animals l)elouging to no 



' Ann. & Alag. Nat. Hist. ser. 6, vol. ix. p. .'jUl (1882). 

 - Troscbi-ra Arcliiv, i. p. 10(5 (1873). 



