'■>.t~,-r 



gEsus geoMalacus, 



body; the ckphalic ketkactors, though resembling tliose of Arioii, have 

 a longer pharyngeal muscle, which is basally fixed behind the right 

 onnnatophore. The renal organ or kidney completely surrounds or 

 encloses the heart, which is, therefore, centrally placed in regard to that 

 organ, as in Ar'wii. 



Food and Habits. — The Gmmdluc! 

 would appear naturally to subsist en- 

 tirely upon the lichens and liverworts, 

 but in captivity they will live and thrive 

 on other and quite different food. 



In their native habitat they are very 

 perfectly protected by their mimetic 

 resemblance to their surroundings, and 

 by their nocturnal and crepuscular 

 habits of life. 



Fossil. — Fossil remains attributed 

 to Geomulucus and named pUcuvnicus: 

 by Sacco, have been found in the Upper 

 Pliocene beds of Fossana, Piedmont. 



Geographical Distribution. — The 



Geomalaci embrace but few species, and 

 these are conhned to the west of Europe, 

 though allied sub-genera have been found in north-west Africa. 



The geological evidence of the former extension of the group is as yet 

 but slight, but the finding of remains referred to Geoimtlucus in the Upper 

 Pliocene of Northern Italy leads us to infer that the genus had formerly a 

 more eastern range, and it is probable that the evolutionary area of the 

 genus was practically identical with that of Arion and the Limacidw 

 generally,- but Geoimdarus is evidently a decadent and waning group, and 

 has by stress of competition with more dominant forms become restricted 

 to the extreme west of Europe, a last foothold heralding their final 

 extinction. 



The genus Anadenus now expelled to the Himalayas is a closely-related 

 but more primitive form than GeoiiKditcas, but which on account of the 

 easterly direction of its enforced ujigration, will probably outlive that group. 



Fig. 253. — Muscular system oi GcomaliKus 

 (after Simrotli.) 



^.r. genital retractor ; k. kidney, enclosing 

 heart; l.i/i. left tentacular retractor; r.in. 

 right tentacular retractor ; p.jn. pharyngeal 

 retractor. 



-^y^ 



Autograph of Mr. \V. AiulrtiWs, ilie dir^covcrer o^ Gcvii/aiams iii-i, k/osus. 



