ASHFORD : ON THE DARTS OF BRITISH HELICIDiE. 24 1 



a dart, attached as usual to the tubercle, the apical half having 

 been lost, probably broken off in conflict. 



I have had no opportunity of observing the occurrence of 

 the dart except in May and September, but during those months 

 only one sac was found empty among about three dozen full- 

 grown shells. 



Mr. H. P. Fitzgerald has obligingly forwarded examples 

 from the neighbourhood of Basingstoke, N. Hants., and fig. i 

 is drawn from one of them. The other figures are from Surrey 

 specimens. 



15. Helix rufescens Pennant, pi. ix., figs. 9 — 12. Dart-sacs 



two in number, one on each side of the vagina, a 

 smaller and empty sac in each case intervening, white, 

 sometimes minutely spotted, slightly transparent. 

 Darts two, usually more or less curved but often 

 straight ; shaft round and smooth, the middle part 

 nearly cylindrical or conspicuously tapering, without 

 blades ; base long, largely expanded, often transversely 

 ridged or puckered ; annulus absent. Length about 

 i"25 mm. 



We now come to a small group, embracing this and the two 

 following species, characterized by a somewhat more complex 

 organization. They all possess two pair of sacs, of which the 

 inner members are empty, and the outer ones secrete darts 

 (fig. 9). We call to mind the two simple sacs of IT. ericetoriim, 

 each containing a dart, and the single bilobed organ oi H. fusca, 

 with its one weapon in the outer lobe. The three Helices now 

 coming under notice may be said to exhibit both these peculi- 

 arities combined in one arrangement. Several continental species 

 closely allied to one or other of the trio appear to have a similar 

 conformation. 



The true dart-sacs of H. rufescens are clavate or pyriform 

 and semi-transparent white, the two secondary lobes are rather 

 smaller than the former, but rise higher and are often more 

 opaque. Both are sometimes densely but minutely spotted with 

 brown. 



R 



