246 ANIMAL PAEASITES. 



Distomum. But how he could have referred to the place where 

 Von Amraon speaks of Distoma ophthalmobium under Monostomum, 

 and alleged under Monostomum lentis that the Distoma treated of 

 by Von Ammon might perhaps be a Monostomum, must be difficult 

 of comprehension by any one who compares Von Ammon' s plates. 

 It would have been more correct had Diesing cited the passage 

 in Nordmanii under Distoma ophthalmobium, and written amongst 

 the literature of this animal, " Monostoma, Von Nordmann (?)." 

 It is also a question, as I have observed above, whether in the 

 case of this Monostomum we hav% to do with a trematode worm 

 at all, and not rather with a young Cysticercus celluloses. As 

 long as 1848 or 1849 I found in the cyst of a large Cysticercus 

 of the rabbit, a small worm with a single structure resembling a 

 mouth at the anterior extremity of its body. Even then I 

 regarded this organism as a young Cysticercus, although Von 

 Siebold assured me that from its form the worm could only be 

 regarded as trematode. Since that time I have examined 

 hundreds of spontaneously bred young Cysticerci, and observed 

 that before the hooks and sucking discs grow in them, and before 

 the well-known collection of nutritive fluid takes place in their 

 interior in larger quantity, they form organisms, which bear an 

 inversion at the anterior part of the body, possessing a deceptive 

 resemblance to a mouth, so that we might well think that we 

 had a Monostomum before us. Whoever has repeated the experi- 

 ments of breeding Cysticerci will admit that I am right with 

 regard to the possibility of this illusion. 



Literature. Von Nordmann, ' Mikrograph. Beitrage/ Heft ii, 

 Vorrede, p. ix. 



Familia II. Distomea = Tribus II. Monocotylea ; 

 XIX. Distomum (Diesing). 



Corpus depressum, vel tertiusculum, armatum vel inerme. 

 Caput continuum, vel collo discretum. Os terminate, vel anticum, 

 ut plurimum acetabuli forme. Acetabulum unicum ventrale sessile, 

 vel pedicellatum medianum, ab ex tr emit ate postica plus minusve 

 remotum. Aperture genitales approximate, scepissime ad eocitum 

 conjunct^ (cloaca instructs), supra vel infra acetabulum sitae. 

 Animalia plerumque hermaphroditica, rarissime sexu distincto. 



