ScHAEFF — On the Slugs of Ireland. 551 



medius is a most typical fungus-eating slug, and I have chiefly found them on 

 species of Riissiila, Agariciis, and Clavaria, 



General Distribution. — Great Britain, Scandinavia, Germany, France, Italy (?), 

 and probably introduced in New Zealand. 



Genus V. Geomalacus, AUman, 1846. 



Body sub-cylindrical; pulmonary opening on front of middle of mantle. Genital 

 pore near base of upper tentacles. Caudal gland opening by transverse slit. There 

 is a solid internal shell. 



This genus was established by Allman (1) to include the most interesting of 

 Irish slugs. 



At first sight a Geomalacus looks very much like an Arion, but the end of the 

 body which in that genus is pointed, and contains the longitudinal opening of the 

 caudal gland, is, in Geomalacus, rounded off, so that the caudal gland opens by a 

 transverse slit between body and foot. 



The reproductive pore or genital opening lies close to the tentacles, as in the 

 genus Limax, whilst in Arion,, as we have seen, it is situated near the pulmonary 

 aperture. 



As for the anatomy, the distinctive characters of Geomalacus maeulosus will 

 be mentioned below, so that it remains only to be said that there is a solid internal 

 shell, something like that in Limax, but very different from the calcareous particles 

 found in Ay-ion. Only one species has hitherto been found in Ireland, and it occurs 

 nowhere else in Europe, except in North-western Spain and North Portugal. Two 

 other species of Geomalacus {G. oliveirae and anguiformis) have been found in 

 Portugal, but only short descriptions of their external characters have appeared 

 as yet. 



Mabille (23) in a Paper on the genus Geomalacus, described several species of 

 French slugs, which he believed to be of this genus, but it has already been clearly 

 demonstrated by Heynemann (13) that this view is entirely without foundation. 

 They really belong to the genus Arion. 



Geomalacus maeulosus, Allman. 



Geomalacus maeulosus, Allman, Ann. and Mag. Nat. Hist. 1846. Geomalacus 

 maeulosus, Jeffreys, Brit. Conch. 1862. 



(Plate LVI., fig. 24.) 



Colour dark gray, with light yellow or whitish spots on body and mantle. 

 External Characters. — The figures given by Heynemann (13) in his excellent 



