526 ScHAEFF — On the Slugs of Ireland. 



Europe which may, with our two species, A. agrestis and A. laevis, be united into one 

 grou}), differing in many important features from the genus Limax. Tlie name 

 Agriolimax has been adopted by such authorities as Simroth (38), Lessona and 

 Pollonera (21), and Malm (25), although it is not by all of them used in the same 

 sense. I have adopted Simroth's definition of the genus. The differences in the 

 intestine alone are sufficient to separate the two forms A. agrestis and A. laevis from 

 the Limaces, but there are additional and not less important differences. Agrio- 

 limax has only four convolutions of the intestine instead of six, and these four are 

 altogether different in position from those in Limax. In the last genus the left 

 lobe of the liver formed the apex of the intestinal sack ; in Agriolimax it is the 

 right. The reproductive organs do not show any very important difference in the 

 two genera, with the exception, perhaps, of the retractor muscle of the penis. The 

 chief objection to the more general recognition of this genus among Malacologists 

 seems to be in the difficulty of fixing a constant character by which Agriolimax 

 may be distinguished from Limax externally. Simroth (38), however, has shown, 

 in his excellent monograph, that the species of Agriolimax never at any period of 

 their lives possess bands. If in some varieties the irregular concentrations of dark 

 pigment here and there appear to produce a kind of lateral band, we must not be 

 led astray by appearances. In the genus Limax, on the other hand, lateral bands 

 are always present, at any rate during youth. They may in later stages unite or 

 break up into irregular spots, but in almost all cases their presence can be easily 

 demonstrated. 



The food in Agriolimax is different from that of the Limaces. As we have seen 

 the natural diet of the latter is probably fungi and lichens, but Agriolimax lives 

 on the higher phanerogamic plants. It is a most destructive pest in the field 

 and garden, whilst the Limaces are comparatively harmless; indeed, they might 

 even be called useful slugs. 



Synopsis of the Irish Species of Agriolimax. 



I. — Mantle about one-third the length of body. Mucus milky = A. agrestis. 

 II. — Mantle about one-half the length of body. Mucus colourless = A. laevis. 



Agriolimax agrestis, L, 



Limax agrestis. Linnd, Sgst. Nat. 1758. Limax agrestis, Jeffreys, Brit. 

 Conch. 1862. Agriolimax agrestis. Malm, Limacina Scandin. 1868. 



(Plate LVL, figs. 5 and 6). 



Body-colour generally of a yellowish-white, irregularly spotted with gray, 

 sometimes of a uniform gray or brown ; mantle about one-third the length of body. 

 Slime milky. A coecum in intestine. 



