OF LIMAX AGBESTIS, ETC. 575 



Yenisei, 'M^m. Acad. St. Petersbourg-,' 187:^, p. 48, as to this 

 eminently social mollusc : ' In einem faulen Treibholzstamm auf 

 den grossen Brjochow Insel (70° N. Br.) in einem Exemplar gefun- 

 den.' But, per contra, in Amoorland, Schrenk tells us, 1. c, that 

 Limax agrestis outnumbers Arion hortensis, just as Arion hortensis 

 outnumbers Limax agrestis in Sweden, Finland, and Lapland, and 

 that while Limax agrestis spreads into Spain, Portugal, Italy, 

 Algeria, and the southern slopes of the Caucasus, Arion hortensis 

 reaches no farther south than the southern slopes of the Pyrenees 

 and Alps. 



In a letter published in the ' Times,' April 14, 1880, and repub- 

 lished with certain omissions in the 'Zoologische Anzeiger,' May 24, 

 p. 258-260 (Article XXXII), I suggested that Arion ater may be the 

 ^ ZwiscJienwlrth^ or one ^ Zwischenwirth,^ io Fasciola Jiepatica. For, 

 calling the small black slug upon the distribution of which I have, 

 following Schrenk and Middendorff, just been writing, ' Arion ater, 

 I have the example and authority of Forbes and Hanley, and I 

 think that of Gerstfeldt. But now, following Schrenk more 

 closely, I should call it Arion hortensis, and should wish to be 

 understood to be of opinion that it will — as I hope, by means of 

 experiments now being carried on in my laboratory by Mr. A. P. 

 Thomas — be ultimately shown that the smaller of our two British 

 Arions really is one at least of the hosts infested by the sheep- 

 fluke, Fasciola hepatica ^. 



As regards the distribution of the Fasciola hepatica in northern 

 regions we have the authority of Leuckart, ' Die Menschlichen 

 Parasiten,' i. p. ^'^\, 1863, for saying that it is found in Greenland 

 and North America ; and the same excellent authority quotes (1. c, 

 ii. p. 87O5 1876) Krabbe to the effect that it is not found in Iceland. 

 The last statement is confirmed by Jonsson in ' Deutsche Zeitschrift 

 fiir Thiermedicin und vergleichende Pathologic,* Bd. v. Heft vi. 

 1879, p. 413, in the words 'Leberegeln kommen in Island nicht 

 vor.' I wish to add that there is no mention of the disease which 

 Fasciola hepatica causes in Olafsen's and Povelsen's two volumes of 

 * Travels in Iceland,' though the diseases of sheep are repeatedly 

 treated of by those authors^. ' And a similar remark may be made 



^ [From the editorial note appended to the immediately preceding Article, it will 

 be seen that Mr. Thomas's experiments resulted in the conclusion that Limnaeus 

 iruncatulus is the intermediate host, — Editor.] 



^ See German translation published in 1794, i. pp. 112-280; ii. pp. 46, 198, 199. 



