cockerell: revised list of British slugs. 69 



ARIONID^. 

 Arion Fer., 1819. 



A. (ater subsp.) empirlcorum Fer., 1819. 



Note. — Pollonera has shown that the true ater differs 

 somewhat from evipiricorum in its genitaha, amounting, I 

 think, to a subspecific distinction. Our form, at least in 

 the South of England, is certainly empiricorum. We get 

 three main subspecific forms of ater in Europe, ater of the 

 North, empiricorum of the central regions, and sidcatus 

 with its allies in Portugal. 



A. subfuscus (Drap., 1805), Mich., 1831. 



A. intermedius Norm., 1852. 



Note. — This is the species lately introduced as A. 

 minimus Simroth, 1885. 



A. hortensis Fer., 1819. 



A. circumscriptus (Johnston, 1828), Fe'r. 



Note. — This is certainly what we usually call A. 

 bourgiiignati Mab., 1868. The British form of ^(?/^rt,''/^4''''^a// 

 agrees with circumscriptus^ and is not keeled in the adult 

 state. Mr. Pollonera, to whom I mentioned this reference, 

 writes me that our species, lacking a keel in the adult state, 

 can hardly be bourguignati, but may be his A. ambiguus. 

 It does not, however, agree with his figures of Arion 

 ambiguus, and specimens of bourguignati he kindly sent 

 me from Ceresole Reale, Piedmont, appear to me to be 

 quite identical with our species. It still remains doubtful, 

 allowing that bourguignati = circumscriptus, whether the still 

 earlier name, A. fasciatus (Nilsson, 1822), should not be 

 preferred, for, as Mr. Pollonera writes me, although Nilsson 

 confounded several species under fasciatus, his type was 

 the true bourguignati. 



GEOMALx\CUS AUm., 1842. 

 G. maculosus Allm., 1846. 



Note. — Among the Irish examples of this species in 



