401 



On referring however to the Prodroraus itself as published in 

 Danish in 1857, I find that the entry which concerns us stands simply 

 thus : »Mollusca Grönlandica 

 Order 1. Geophila, 

 » Gen. 1. Limax L. 



*L. agrestis'L. (ifolge Wormskjold) , 

 *Betigner at Arten's Forekomst paa Grönland ikke er sikker.« 

 Here we see that the line in the entry given in the Manual of 1S75 

 »Arion fuscus Müll. Probably introduced« is altogether something 

 fresh and new, whilst the asterisk denoting that the animal so marked 

 is possibly not indigenous has been removed from the Limax agrestis 

 and prefixed to the curious name y)Arioti fuscus Müll.«. 



It is difficult to understand, how the late Dr. O. A. L. Mörch can 

 have come in 1875 to alter his previous entry in this manner. For the 

 name »Ariona was unknown to Müller, the author of the Historia 

 Yermium, having been introduced into Malacology by Féru ss ac as he 

 himself tells us Hist. Nat. des Mollusques. 11. 1820 — 1851. p. 23 

 and 54, and as regards the animal itself, on the supposition that 

 Dr. Mörch by his entry ^^ Avion fuscus Müll.« intended to have written 

 Limax fuscus Müll, and knowing that this Limax so called by Müller 

 was really an Arioii hortensis and not a slug with a posteriorly placed 

 respiratory inlet and a continuous shell , it is still more difficult to see 

 hoAv he could have left standing the Avords -oLimax agrestis L.« appa- 

 rently as a synonym. For in the 13th Edition of the Systema Naturae 

 Tom. 1. pars \T. p. 3101 — 3102 the (true) y> Limax agrestisa is distin- 

 guished from the r> Limax fuscusv. (= Avion hovtensis hodie) of »Müller 

 hist. verm. H. p. 11, n. 209«. On referring to Dr. O. A. L. Morch's 

 Faunula Molluscorum Islandiae, communicated on the 13th April of 

 1866 and published in 1868 in the Danish Vidensk. Medd. fra den na- 

 naturhist. Forening, I. Kbvn. p. 185 — 227, I find at p. 196, 3. that 

 y>Limax agvestis L.« stands with a ? after its name, even though there 

 can be no doubt from references to Olafsen, several of which are in fact 

 given by Mörch, that a grey slug as well as the black slug Avion atev 

 exists in Iceland. The words at the end of the entry make me think 

 that Mörch may have intended to hint that this Limax was not Limax 

 agvestis but Limax tenellus. The words are »Et exerapl, taget af Hall- 

 grimson er muligvis Limax teiielkis-a 



Perhaps therefore the true explanation of the entry in the Manual 

 of 1875 is as follows : in the interval between 1857 and 1875 a black sluo- 

 may have been proved to Dr. M ö r c h 's satisfaction to have been found 

 in Greenland . anti he may have identified it as the Avion fuscus of 

 Moquin Tandon, which is the same as the Avion hortensis of Férussac and 



