19? 



JOURNAL OF CONCHOLOGY. 



Vol. 14. JULY, 1914. No. 7. 



NOTES ON THE CANDIDULA SECTION OF HELICELLA. 



By J. WILFRID JACKSON, F.G.S. 



(Read before the Society, January 14th, 1914). 



The Candidula Section comprises a large number of species of small 

 Helicellae of which the most familiar to British collectors is the Heli- 

 cella caperata (Montagu). 



The sectional name Candidula was proposed by Kobelt in 187 1 

 (Catalog., p. 22), but various members of the group have at different 

 times been described under other sectional names, such as Helicopsis, 

 Striatella, etc., while in 1892 Monterosato proposed a number of new 

 sectional 'names all beginning with Xero — . 



The type of the section is H. candidula Studer. 



Like many of the allied sections of Helice/Ia, the group contains a 

 large number of indefinite species, mostly founded on slight individual 

 variation, or on young examples of well-known forms. 



The intricate synonymy of the group, and the dearth of data for 

 discrimination on anatomical grounds renders it extremely difficult 

 for the serious student to decide upon the correct name of any 

 particular species. The species are very numerous throughout Middle 

 Europe and the Mediterranean region, and at least two species are 

 living in the British Isles. 



In some parts of their anatomy they present features linking the 

 members of this and other sections of Helicella with Hygrojiiia. The 

 chief among these is the simple form of dart and the frequent dupli- 

 cation of the dart sac. Pilsbry^ points out that in the Candidula 

 section it is probable that two sections will be distinguished, the 

 division to be based on the number of dart sacs ; but at present so 

 few species have been dissected that such division is not possible. 



In this paper I propose to discuss only the two British species, 

 H. caperata and H. gigaxii, and the type species of the Section, H. 

 candidula. 



I Tryon's " Man. Conch.," ix., p. 254. 



