INTRODUCTION. XVll 



and in the same list includes "Arion subflamis" without description, in 

 addition to Arion ate?-, thus ignoring not Only Arion hm-fensis but his own 

 Arion circumscriptus. 



In 1840 Dr. Gray published his so-called new edition of Turton's 

 Manual, in reality a new work, and in this he sank Arion circumscriptus 

 and Testacella scutulum as being but slight varieties, and also excluded 

 T. maugei as non-indigenous. 



But in the same year, 1840, a new enthusiast and very capable investi- 

 gator appeared, who may be regarded as our first British limacological 

 specialist. The Rev. B. J. Clarke took up the detailed study of the Irish 

 slugs, and in the " Annals and Magazine of Natural History " for 1840 

 and 1843 he established the existence of two new British species of which 

 there had not previously been any indication in our literature : 



12. Limax arborum. 



13. Milax gag-ates. 



His papers also include indications of Arion subfuscus and Limax cinereo- 

 niger, as well as show that the author was aware of the presence in Ireland 

 of Arion circumscriptus and Testacella maugei, although he did not venture 

 to reinstate them as species. 



In the same year, 1843, Limax arborum is first mentioned as Scottish 

 in Macgillivray's " History of the Molluscous Animals of Aberdeen, 

 Kincardine, and Banff." 



In 1842 an important discovery was made by Mr. W. Andrews in the 

 form of the remarkable new slug, which in 1848 Dr. G. J. AUman described 

 with a full anatomical account as 



14. Geomalacus maculosus. 



In 1848 Mr. Joshua Alder's "Catalogue of the Mollusca of Northumber- 

 land and Durham" was published in the Tyneside Field Club Transactions. 

 It is a work of great importance to us, as in it were brought forward two 

 species new to Britain : 



15. Arion intermedius, 



16. Limax tenellus, 



and there is also a distinct reference to the slug we now know as Arion 

 subfuscus. 



These additions mark the close of the earlier periods of the active 

 scientific investigations of our British slugs, for although malacologists 

 generally were by no means inactive, and numerous manuals were pub- 

 lished including those of Brown in 1845, Leach in 1852, Forbes and Hanley 

 in 1853, Gray's Turton in 1857, Jeffreys in 1862 and 1869, Reeve in 1863, 



