190 ASHFORD : ON THE DARTS OF BRITISH HELICID^. 



The dart (fig. 7) is as fragile in substance as it is elegant in 

 form, and must be isolated by boiling the sac in the usual solution 

 of caustic potash. Different as are the shells of this and the last 

 species there are more points of resemblance in their internal 

 organisation than here described or usually supposed, and a 

 reference to the figures will show that their darts are distinguish- 

 able only by the proportion of the several parts. In the present 

 case the head is smaller, absolutely and proportionately, occupy- 

 ing scarcely more than one-fourth of the entire length of the dart, 

 and is flatly compressed with sharper and more transparent 

 margins. I have frequently noticed too an opalescent play of 

 colour on the polished surface of the head when fresh from the 

 dart-sac, but the appearance is fugitive. 



I am indebted to Mr. J. H. Ponsonby for living specimens 

 from Yatton in Somersetshire, and I have examined a consider- 

 able number from Epsom in Surrey^ sent by my late corre- 

 spondent Mr. J. E. Daniel, and from Swanage, collected by my 

 brother. About 66 per cent, had darts in July, August, and 

 September. 



The figures are drawn from the Yatton and Swanage 

 examples. 



12. Helix pulchella Miiller, pi. viii. figs. 8, 9. Dart-sac 

 elongate oval ; pellucid white. Dart straight, very 

 acutely conical^ without accessories of any kind (?). 

 Length 0.2 mm. 



The following information respecting the organs in ques- 

 tion in this species is offered subject to confirmation or correc- 

 tion. Further examination is desirable. 



When the dissection turned out favourably the dart-sac 

 (fig. 8) appeared to be rather long and narrow, broadest in the 

 middle and somewhat pointed. I could detect no mucous 

 glands, and Moquin-Tandon says there are none, though in his 

 diagnosis of the subgenus Lucena, of which he makes H. pul- 

 chella the only French representative, a note of doubt is added 

 to the same statement. 



J.C, iv., July, 1S84. 



