TURBELLARIA. 9 



D. lacteum, Oerst. Corpus antice emarginato-truncatimi, 2JosHee 

 acutninatum. album, rosaceuon I. riolaceum,; in medio macula laefea (oe- 

 sophagus). Lg. 7 — 10; laf 2 — 3 m. m. 



Syn. Hii'Lido depressa alba, lateribus acutis, Limie Goth. p. 182 

 (nondum 250i ; F. Su. i. p. 165 M 1274 ex parte. 



Fasciola liepatica, Linnt' F. Su. n. p. 505 M 2073 (ex parte); 



Lin. S. Nat. X p. «48. 

 Fasciola lactea, 0. F. Miiller i. n. 61. ■ 

 Planaria lactea, Fabricius F. aroen. 327; Linne S. Nat. xni 3090; 



DiesiDg I. 203; G. Johnston p. 10. 

 Dendi'Dcoelum lacteum, Oersted 51; Diesing W. S. B. Bd 44. I. 



p. 504. 

 Planaria arethusa, G, Johnst. p. 11. 



Habitat una cum prsecedente, ubique frequeatissimiim. 



Obs\ This specie.s occurs, as is already told, of various 

 colours. I have met with four chief varieties, viz. a nornialis 

 — lactea, ^ plumbea-arethusa, Johnst; y rufa and 8 fusco-cine- 

 rea; and I have very often been able to state that the, when 

 caught, gaily coloured animals, after one or two weeks, by litt- 

 le and little, have lost tlieir colour and grown quite white as 

 snow, to such a degree, that the ramifications of the intestins 

 were to be seen ouly with great difPiculty. Thus it seems to 

 me that G. Johnston is entirely right, when (p. 10) imputing 

 the colour of those animals to their food; but it is yet to be 

 shown what kind of food gives rise to the different colours; as 

 I often have caught all the above mentioned varieties promis- 

 cuosly on the same stone. According to Gerstfeldt at Irkutsk for 

 this species vicariates Planaria angarensis, Gerstf. 



r am. POLYCELIDEA, Diesing. Corpus depressum,; ptede venfrali nullo 

 aut uno. Caput corpore continuum vel diseretimi, aurioulatum I. exau- 

 rieulatmn, tentaculis nullis Oeelli vj vel numerosi Os ventrale, ante 

 vel pone medium corporis situm; oesophago cylindrico vel campanidato. 

 Apertura genitalis unica pone os. Aquarum duleium ineolae vel terrestria. 



Polycelis, Ehbg. Cor2ms planum, latum; ocelli pluriftni, ad mar- 

 g'rnem corporis glahri anteriorem; os plerumqve ptosticum. 



P. nigra, Ehbg. Corptus antrorsum obtusion, retrorsnni p>aulhdum 

 attenuatum, fuscmm, I. brumieum. Lg 6 — 11 m. m,, lat. 3 — 4 m. m, 



Syn. Fasciola nigra, 0. F. Miiller i. n. 54. 

 Planaria nigra, Linne S. Nat. xill 3087; Oersted 54. 

 Polycelis nigra, Diesing i. 191; G. Johnston p. 9. 

 Polycelis brunnea et felina G. Johnston p. 9 & 10. 



Habitat in aqua vel dulci (Helsinge) vel subsalioa (Runsala). 

 Obs\ According to the characters given by Johnston the 



