346 Prof. P. J. Van Beneden on the Intestinal Worms. 



■stoma belongs, are propagated in two ways — by germs in the 

 non-sexual generation, and by eggs in the sexual. These arc 

 small and very numerous. The embryo is always covered with 

 cilia (this form is named Proscolex), and for a time lives freely 

 in the water. From this embryo a vermiform creature proceeds 

 that might almost be named a germ-sac (sporocyst) ; it lives 

 parasitically in closed cavities, and is named Scolex by our au- 

 thor. The numerous germs which are developed in this germ- 

 sac, and are provided with a filiform appendage, a tail, again 

 live freely in water. They are the well-known Cercarice — here 

 named Proglottis', they enclose themselves in a cyst, and, losing 

 their tail, are now changed into Distomata, which again live 

 parasitically, but in cavities of the body that open freely out- 

 wards, as in the respiratory organs or the intestinal canal. 



Of these Trematodes dir/eneses the following species are here 

 described : Munostoma mutabile, Monostoma verrucosum, Amphi- 

 stoma subclavatum, Distoma viilitare, Distoma echinatum, Distoma 

 retusum, Distoma clavigerum, Distoma tereticolle, Distoma filicolle 

 [Monostoma filicolle), Rud., Distoma Okenii, Kolliker, and Ne- 

 matohothrium filarina. Of most of these the different forms of 

 embryos, sporocysts, and cercarise are given. To Distoma militare 

 V. Beneden refers the Cercaria pacifica, which Steenstrup had 

 figured in his well-known work on alternating propagation ; the 

 sporocysts and cercarise are met with in Paludina vivipara, whilst 

 the Disto7na -form is found in the intestinal canal of Anatidce and 

 other water-birds, and of snipes. The cercaria-{oY\w& of Distoma 

 retusum and D. clavigerum have been confounded under the 

 name of Cercaria armata. Of Distoma filicolle two are com- 

 monly found in one cyst, on Brama Raji of the Mediterranean 

 Sea ; they are very unequally developed : the one ends in a wide 

 sac, which is bent into a curve, and resembles the body of a 

 larva of the cockchafer ; the other is thin, and was supposed by 

 lludolphi to be an imperfect specimen — the neck without the 

 body of the worm (Synopsis Entozoor. p. 348). Nematobothrium 

 is a new genus, found, like the above-named genus Calceostoma, 

 by V. Beneden on Scicena Aquila. It is a long, thin, soft worm 

 (about 1 metre long), which, rolled up into a pellet, lives under 

 the skin near the gills. This worm forms as it were the trans- 

 ition to the Cestoids. V. Beneden could not discover any intes- 

 tinal canal, but thinks that it may have been present in some 

 earlier state of existence, before the sexual organs were entirely 

 developed. 



With the Cestoids or tape-worms, V. Beneden adopts a similar 

 distinction or division as with the Trematodes. According to him, 

 they may be distinguished as Cesto'ides monogeneses and Cesto'ides 

 digeneses. To the fii-st belongs the genus CaryopMjllcms alone 



