ARION. 



ARION, Ferussac. 



Animal elongated, semi-cylindrical, furnished anteriorly 

 with an oblong- disk. Head with four tentacula, the two 

 upper ones furnished with eyes ; mouth with a serrated 

 corneous tooth. Respiratory orifice at the anterior margin 

 of right side of the disk ; the vent immediately behind it. 

 Orifice of reproductive organs immediately below the re- 

 spiratory aperture. Posterior extremity of body rounded, 

 terminating by a slight truncation, and a mucus pore. 

 Shell undeveloped ; a few calcareous granules sometimes 

 imbedded in substance of shield. 



Besides the above differences, the slugs of this genus 

 differ in several important anatomical characters, from 

 those of the next group. Their habits are similar. 



A. EMPiRicoRUM, Ferussac. 



Body bulky ; shield ovate ; margin of foot expanded and 

 lineated ; mucus pale. 



Plate D. D.D. fig. 4. 



Liviax (iter,, alius et succineus, Muller, Hist. Verm. vol. ii. pp. 2, 4, 7. 



„ „ ru/us et suhfuscus, Draparnaud, Moll, de France, pp. 122 and 

 123, pi. 9, f. 3, 4, fi, 8. 

 Avion „ Gray, Man. p. 104. — Alder, Cat. Northumb. Moll. p. 29. — 

 Macgillivray, Moll. Aberd. p. 73. — Nunneley, Leeds Trans, 

 vol. i. pi. l,f. 1. 

 „ cmpirieorum, Ferussac, Hist. p. 60, pi. 1 to 3. — Bouchard Chante- 

 reaux, Mem. Soc, Ag. Boul. 2nd ser. vol. i. p. 157. — 

 Brown, 111. Brit. Conch, p. 55. 



This very common, beautiful, and exceedingly variable, 

 slug, has been so cut up into false species, on account of 

 its caprices of colour, that we deem it right to follow the 

 example of Ferussac, and to give it a name which may 



