JOURNAL OF CONCHOLOGY. 1 29 



THE DARTS OF BRITISH HELICID^. 



By CHARLES ASHFORD. 



PART III. 



[Correction. — In pi. ii., fig. i, the reference letter "/" has 

 been, by error, placed near the duct of the spermatheca. 

 It should be near the whip-like organ on the left. The 

 explanation at the foot of the same plate does not clearly 

 state that fig. i only has special reference to H. hortensis.'\ 



4. Helix ericetorum Miiller, pi. v. figs, i — 5. Dart-sacs 

 two in number, each simple ; lower parts tused to 

 vagina, free ends ovate, bluntly pointed ; greyish- 

 yellow, speckled with minute brown dots. Darts like 

 simple tubes, curved, twisted; head sometimes com- 

 pressed; base not expanded ; annulus absent. Length 

 4 to 5I mm. 



This is the largest of our four species furnished with a pair 

 of darts, and the only one having two simple dart-sacs (fig. i). 

 These sacs are liable to modifications. Sometimes they are of 

 unequal length, and I once found one member of the pair very 

 small — perhaps atrophied — the other being of usual size. 

 But I never met with them so distinctly separated as repre- 

 sented by Martin Lister (Exer. Anat.), and by Ad. Schmidt. 

 They are surmounted — rather high up — by a verticillate corona 

 of slender, generally simple, sometimes bifid mucous glands, 

 varying from 8 to 1 1 in number. In one case I counted nine, 

 with a total of 18 branches. The papillary common outlet of 

 the dart-sacs may frequently be distinguished through the in- 

 vesting coats with the points of the two weapons protruding 

 from it. 



The darts (fig. 2) are stout, sharply pointed, and large for 

 the size of the animal. Only those of mature growth show a 

 flattened head (fig. 3). The amount of compression varies, but 

 the lateral edges do not develope into blades. Both Busch and 



