collinge: a review of the arionid.e of the British isles. 77 



It is very questionable whether this form exhibits sufficient 

 anatomical differences to justify its being separated from A. hortensis. 

 It was figured and described by Pollonera in 1887 (29), but Simroth 

 (41), who has also examined specimens, thinks there is no difference 

 between it and A. hortensis. His figure of the reproductive organs 

 differs entirely from that given by Pollonera. 



Mr. Cockerell (8) pointed out some little time ago that 

 A. celticus might be expected to occur in the south-west of England 

 or the south of Ireland. Since then I have dissected a number of 

 forms very closely resembling Pollonera's figures and description. 

 In April last Dr. Scharff very kindly sent me examples of Irish 

 Arionidcs, one example of which he thought might be A. celticus ; 

 externally it was very like Pollonera's figure, but the general 

 anatomy agreed with A. hortensis. Specimens received from the 

 south of Oxford and from Middlesex were compared with the original 

 figures, but anatomically they were not constant enough to warrant 

 me in saying they were A. celticus, although very closely allied. 

 I have, however, received from Mr. E. W. Swanton examples from 

 Doddington, Kent, and from Southampton, agreeing in all particulars 

 with the original figures and description. Specimens received from 

 Signor Pollonera from Brest, France, agree with those from 

 Southampton in almost every detail. 



Arion cottianus, Pollonera, 1889. 

 U A hortensi proximus, a quo differt staiura panlulum minore, 



dorso minus n/goso, solea subtiliore." 

 "A leviter rugosus, sordide griseus, medio fuscatus, lateraliter atro- 

 castaneo zonatus et reticulatus. Solea subtilissima, pallida ; 

 margine externa angusto {flavo T), postice nigro-punctulatc, et 

 sublineolato, ad glandulum caudalem nigrescente. Limacella 

 nulla. Long, {in alcool) 15 mill.'" 

 This interesting species was figured and described by Pollonera 

 (30) in 1889. Mr. E. W. Swanton sent me three examples of this . 

 slug in June last from Southampton!. A dissection of one made by 

 myself agreed with Pollonera's figure and description, and Dr. Scharff 

 very kindly made a dissection of a second specimen and agrees with 

 my determination. The above three specimens measured respectively 

 35, 36, and 37 millm. when alive, and about 25 millm. in alcohol. 



Arion fasciatus, Nilsson, 1822. 

 Limax fascia/us, Nilsson, Hist. Moll. Sueciae, p. 3, 1822. 

 Arion hortensis, var. alpicola (partim), Ferussac, Hist. Moll., pi. viiiA, 

 fig- 4, 1823. 

 ,, circumscriptus, Johnston, Edinburgh New Philosoph. Journ., 

 p. 74, 1828. 



