MACDONALD \ ON THE CLASSIFICATION OF VARIETIES. 27 



Anatomy. — The reproductive organs are generally larger than in 

 the type. The most constant features are the shortness of the 

 receptacular duct, the enlarged lower vestibule, and the globose form 

 of the lowest portion of the sperm duct. In some — five specimens — 

 the oviduct was very characteristic, showing a well marked difference 

 in size between the upper and lower portions ; in others, however, 

 it varied greatly. 



Arion circumscriptus, Johnst. 

 var. nov. flavescens. 

 Body, light brownish-yellow, dark lateral bands, with light 

 brown or dark yellow stripe below, faint blue stripe above foot- 

 fringe, from head to mucous gland ; head and tentacles, dark 

 blue ; sole, white or bluish-white ; foot-fringe, white, no lineoles ; 

 rugce, large and prominent ; sulci, dark. 

 Length alive, 49 mm. 

 Hab.— St. Andrews, N.B. 

 Found in company with the smaller brown form (var. netislriacus, 

 Mabille. ?). 



ON THE CLASSIFICATION OF VARIETIES. 



By ROBERT MACDONALD, M.A., B.Sc, 

 Madras College, St. Andrews. 



A specialist is almost certain to discover amongst members of 

 a species differences so persistent that he is compelled to recognise 

 them as marks of permanent varieties ; but it seems to me that 

 a variety of a species should be constituted only under compulsion 

 (as it were), since the multiplication of varieties is a loss to simplifi- 

 cation. Now the schedule of classification of varieties of Helix 

 hortensis, Mull., and H. nemoralis, L., proposed by the Rev. W. L. W. 

 Eyre, in last quarter's " Conchologist," is a distinct invitation to form 

 as many varieties as possible — the more numerous they are, the more 

 in accordance with the schedule will the collection be. 



Mr. Eyre gives seven varieties of H. hortensis, based on ground 

 colour alone (of course, seven does not exhaust the number of 

 ground hues, but suppose for argument's sake it does). The lip may 

 vary in colour according to the schedule in five different ways. On 

 these two features alone — ground colour and lip colour — 35 varieties 

 could be made. 



