448 MB. W. B. COLLIXGB ON BTTEOPEAN SLUGS. [May 4, 



CLASSIFICATION. 



Family AEIONID^, Gray, 1840. 



Subfain. Arionin^, "W. Gr. Binney, 1864. 



Genus Aeiok, Ferussac, 1819. 

 Group I. 



1. A. ater, Linne, 1758. (Continent.) 



2. A. rufus, Linne, 1758. (Continent.) 



3. A. empiricorum, Ferussac, 1819. (British Isles and 



Continent.) 



4. A. lusitanicus, Mabille, 1868. (British Isles and 



Continent.) 



5. A. brevierei, Pollonera, 1887. (Continent.) 



6. A. dasilvse, Pollonera, 1887. (Continent.) 



7. A. aggericola, Mahille, 1870 '. (Continent.) 



8. A. flagellus, Collinge, 1893. (Ireland and Con- 



tinent.) 

 Group II. 



9. A. sulifuscus, Draparnaud, 1805. (British Isles 



and Continent.) 



10. A. fuscus, Miiller, 1774. (Continent.) 



11. A. bavayi, Pollonera, 1887. (Continent.) 



12. A. pegorarii, Lessona & Pollonera, 1882. (Con- 



tinent. ) 



13. A. flavus, Nilsson, 1822. (Continent.) 



Group III. 



14. A. hortensis, Ferussac, 1819. (British Isles and 



Continent.) 



15. A. anthracius, Bourguignat, 1866. (Continent.) 



16. A. csBiuleus, Collinge, 1897. (British Isles.) 



17. A. cottianus, Pollonera, 1887. (British Isles ? a 



Continent.) 



18. A. nilssoni, Pollonera, 1887. (Continent.) 



19. A. alpinus, Pollonera, 1887. (Continent.) 



20. A. hessei, Siraroth, 1894. (Continent.) 



21. A. elongatus, Collinge, 1894. (British Isles.) 



Group IV. 



22. A. fasciatus, Nilsson, 1822. (British Isles and 



Continent.) 



23. A. subcarinatus, Pollonera, 1885. (Continent.) 



^ At present this must be regarded as a doubtful species. Mabille placed it 

 in the A. suhfuscus group (16), but Pollonera (21) states that from the radula 

 it belongs to the A. ater group, being a form allied to A. brevierei, Poll., from 

 which it differs by its smaller size, brighter colour, small receptaculum seminis, 

 shorter receptacular duct, and b}- the great length of the sperm-duct. 



